\( 40 \times 2 + 80 = 100 \)
\( 15 + 300 = 315 \)
\( 100 : 20 \times 12 = 60 \)
\( 20 : 4 \times 10 = 50 \)
\( 360 + 40 : 40 = 361 \)
\( 600 + 80 - 1 = 679 \)