Вычисления:

1. a) $$50 + 40 = 90$$
   $$90 : 30 = 3$$
   $$3 \cdot 50 = 150$$
   $$150 - 100 = 50$$
   Ответ: 50
2. б) $$30 + 70 = 100$$
   $$100 : 10 = 10$$
   $$10 - 15 = -5$$
   $$-5 \cdot 150 = -750$$
   Ответ: -750
3. в) $$100 - 70 = 30$$
   $$30 : 3 = 10$$
   $$10 - 18 = -8$$
   $$-8 : 36 = -\frac{8}{36} = -\frac{2}{9}$$
   Ответ: $$\frac{-2}{9}$$
4. г) $$100 - 80 = 20$$
   $$20 : 4 = 5$$
   $$5 - 14 = -9$$
   $$-9 - 67 = -76$$
   Ответ: -76