Answer:
Man's present age: 32 years
Older son's present age: 8 years
Younger sons present age: 4 years
Step-by-step explanation:
Let their present ages be represented by:
Man = a
Older boy = b
Younger boy = c
A man has two sons, one twice as old as the other:
b = 2 × c
b = 2c......... Equation 1
The man is four times as old as the older boy:
a = 4 × b
a = 4b.......Equation 2
In three years he will be five times as old as the younger boy:
a + 3 = 5 (c + 3)
a + 3 = 5c + 15........Equation 3
Since b = 2c and a = 4b
Subtitute 2c for b in Equation 2
a = 4b
a = 4 × 2c
a = 8c
Subtitute 8c for a in Equation 3
a + 3 = 5c........Equation 3
8c + 3 = 5c + 15
Collect like terms
8c - 5c = 15 - 3
3c = 12
c = 4
Therefore since c, represents the present age of the younger son, the younger son is 4 years old
b = 2c
b = 2 × 4
b = 8
Since b is the present age of the older son, the older son is 8 years old
a = 4b
b = 8
a = 4 × 8
a = 32
Since a is the present age of the man, the man is 32 years old
Therefore,
Man's present age: 32 years
Older son's present age: 8 years
Younger sons present age: 4 years
