A boy is 10 years older than his brother. In 4 years he will be twice as old as his brother. Find th

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A boy is 10 years older than his brother. In 4 years he will be twice as old as his brother. Find the present age of each?

Let the boy's age be b and his brother's age be c. We're given two equations:

1. b = c + 10
2. b + 4 = 2(c + 4)

Substitute equation (1) into equation (2):
(c + 10) + 4 = 2(c + 4)

Simplify by multiplying the right side through and grouping like terms:
c + 14 = 2c + 8

Type this equation into our search engine and we get:
c = 6

Now plug c = 6 into equation (1):
b = 6 + 10
b = 16