Sylvia is twice as old as her brother. Find their ages now if in seven years her brother will be what her age was last year.

Answer 1

S = 2B

B+7 = S-1 = 2B-1

B = 8 = brother's age now

Sylvia is 16 years old now

in 7 years brother's age is 15

which equals Sylvia's age last year.