aaron is 13 years older than shelby. in nine years aaron will be twice as old as shelby. how old is shelby?

Answer 1

A = Aarons current age

S = Shelbys current age

A = S + 13

In nine years aaron will be twice as old as shelby:

( A + 9 ) / ( S + 9 ) = 2

( S + 13 + 9 ) / ( S + 9 ) = 2

( S + 22 ) / ( S + 9 ) = 2 Multiply both sides by ( S + 9 )

S + 22 = 2 ( S + 9 )

S + 22 = 2 S + 18

22 - 18 = 2 S - S

4 = S

S = 4