Question 1101123
 the ratio of the father's age to the son's age = 50/20 = 5/2
:
a)  (5/2) * 10 = 25, the father is 25 years old
:
b)  (5/2) * x = 35
x = 70/5 = 14, the son is 14 years old
:
c)  (5/2) * 40 = 100, father will be 100 years old
:
d)  (5/2) * x = 75
x = 150/5 = 30, son is 30 years old
: