Решим примеры, расставив скобки, чтобы равенства стали верными.
* 140 - 80 : 4 × 5 = 75
140 - (80 : 4) × 5 = 75
140 - 20 × 5 = 75
140 - 100 = 75
40 = 75 – неверно.
140 - 80 : 4 × 5 = 75
(140 - 80) : 4 × 5 = 75
60 : 4 × 5 = 75
15 × 5 = 75
75 = 75 – верно.
* 140 - 80 : 4 × 5 = 600
140 - (80 : 4 × 5) = 600
140 - (20 × 5) = 600
140 - 100 = 600
40 = 600 – неверно.
140 - 80 : 4 × 5 = 600
(140 - 80 : 4) × 5 = 600
(140 - 20) × 5 = 600
120 × 5 = 600
600 = 600 – верно.
* 140 - 80 : 4 × 5 = 136
140 - 80 : 4 × 5 = 136
140 - (80 : 4 × 5) = 136
140 - (20 × 5) = 136
140 - 100 = 136
40 = 136 – неверно.
140 - 80 : 4 × 5 = 136
(140 - 80 : 4 × 5) = 136
140 - 80 : (4 × 5) = 136
140 - 80 : 20 = 136
140 - 4 = 136
136 = 136 – верно.
* 8 × 30 - 30 : 3 × 5 = 238
8 × 30 - 30 : 3 × 5 = 238
(8 × 30 - 30) : 3 × 5 = 238
(240 - 30) : 3 × 5 = 238
210 : 3 × 5 = 238
70 × 5 = 238
350 = 238 – неверно.
8 × 30 - 30 : 3 × 5 = 238
8 × 30 - (30 : 3 × 5) = 238
8 × 30 - (10 × 5) = 238
8 × 30 - 50 = 238
240 - 50 = 238
190 = 238 – неверно.
8 × 30 - 30 : 3 × 5 = 238
8 × (30 - 30 : 3 × 5) = 238
8 × (30 - 10 × 5) = 238
8 × (30 - 50) = 238
8 × (-20) = 238
-160 = 238 – неверно.
8 × 30 - 30 : 3 × 5 = 238
8 × 30 - 30 : (3 × 5) = 238
8 × 30 - 30 : 15 = 238
8 × 30 - 2 = 238
240 - 2 = 238
238 = 238 – верно.
* 8 × 30 - 30 : 3 × 5 = 0
8 × 30 - 30 : 3 × 5 = 0
(8 × 30 - 30 : 3) × 5 = 0
(240 - 10) × 5 = 0
230 × 5 = 0
1150 = 0 – неверно.
8 × 30 - 30 : 3 × 5 = 0
8 × 30 - (30 : 3) × 5 = 0
8 × 30 - 10 × 5 = 0
240 - 50 = 0
190 = 0 – неверно.
8 × 30 - 30 : 3 × 5 = 0
(8 × 30 - 30) : 3 × 5 = 0
(240 - 30) : 3 × 5 = 0
180 : 3 × 5 = 0
60 × 5 = 0
300 = 0 – неверно.
8 × 30 - 30 : 3 × 5 = 0
8 × (30 - 30 : 3 × 5) = 0
8 × (30 - 10 × 5) = 0
8 × (30 - 50) = 0
8 × (-20) = 0
-160 = 0 – неверно.
8 × 30 - 30 : 3 × 5 = 0
8 × 30 - 30 : (3 × 5) = 0
8 × 30 - 30 : 15 = 0
8 × 30 - 2 = 0
240 - 2 = 0
238 = 0 – неверно.
8 × 30 - 30 : 3 × 5 = 0
8 × 30 - 30 : 3 × 5 = 0
8 × 30 - (30 : 3 × 5) = 0
(8 × 30 - 30 : 3 × 5) = 0
(8 × 30 - 30 : 3 × 5) = 0
8 × (30 - 30) : 3 × 5 = 0
8 × (30 - 30) : 3 × 5 = 0
8 × (30 - 30 : 3) × 5 = 0
(8 × 30 - 30 : 3) × 5 = 0
8 × (30 - 10) - 5 = 0
(8 × 30 - 30) : 3 × 5 = 0
(240 - 30) : 3 × 5 = 0
210 : 3 × 5 = 0
70 × 5 = 0
350 = 0 – неверно.
8 × 30 - 30 : 3 × 5 = 0
(8 × 30 - 30 : 3 × 5) = 0
(8 × 30 - 30) : (3 × 5) = 0
(240 - 30) : 15 = 0
210 : 15 = 0
14 = 0 – неверно.
8 × 30 - 30 : 3 × 5 = 0
8 × 30 - 30 : 3 × 5 = 0
(8 × 30 - 30 : 3 × 5) = 0
8 × (30 - 30 : 3 × 5) = 0
(8 × 30 - 30 : 3) × 5 = 0
8 × (30 - 10 - 5) = 0
(8 × 30 - 10 - 5) = 0
(8 × 30 - 30 : 3) × 5 = 0
30 × (30 - 10 - 5) = 0
8 × (30 - 10 - 5) = 0
(8 × 30 - 30 : 3 × 5) = 0
(8 × 30 - 30) : 3 × 5 = 0
(240 - 30) : 3 × 5 = 0
(8 × 30 - 30 : 3 × 5) = 0
8 × (30 - 30 : 3 × 5) = 0
(8 × 30 - 30) : 3 × 5 = 0
(8 × 30 - 30 : 3 × 5) = 0
(240 - 30) : 3 × 5 = 0
(240 - 30) : 3 - 5 = 0
8 × (30 - 30) : 3 × 5 = 0
8 × (30 - 30 : 3) × 5 = 0
(8 × 30 - 30 : 3) × 5 = 0
(240 - 10) × 5 = 0
8 × 30 - (30 : 3 × 5) = 0
8 × 30 - (10 × 5) = 0
(8 × 30 - 10) × 5 = 0
(240 - 10) × 5 = 0
(230) × 5 = 0
1150 = 0 – неверно.
8 × 30 - 30 : 3 × 5 = 0
(8 × 30 - 30 : 3 × 5) = 0
(8 × 30 - 30 : 3) × 5 = 0
(8 × 30 - 30) : (3 × 5) = 0
(8 × 30 - 30) : 3 × 5 = 0
(240 - 10) = 0 - неверно.
(8 × 30 - 30 : 3) = 0 - неверно.
(240 - 10) × 5 = 0 - неверно.
* 8 × 30 - 30 : 3 × 5 = 350
8 × 30 - 30 : 3 × 5 = 350
8 × (30 - 30 : 3) × 5 = 350
8 × (30 - 10) × 5 = 350
8 × 20 × 5 = 350
160 × 5 = 350
800 = 350 – неверно.
8 × 30 - 30 : 3 × 5 = 350
8 × 30 - (30 : 3) × 5 = 350
8 × 30 - 10 × 5 = 350
240 - 50 = 350
190 = 350 – неверно.
8 × 30 - 30 : 3 × 5 = 350
(8 × 30 - 30) : 3 × 5 = 350
(240 - 30) : 3 × 5 = 350
210 : 3 × 5 = 350
70 × 5 = 350
350 = 350 – верно.
Ответ:
* (140 - 80) : 4 × 5 = 75
* (140 - 80 : 4) × 5 = 600
* 140 - 80 : (4 × 5) = 136
* 8 × 30 - 30 : (3 × 5) = 238
* 8 × (30 - 30) : 3 × 5 = 0
* (8 × 30 - 30) : 3 × 5 = 350