Let Charles age be x
Adam age will be 5x
8 years later , add 8 to both expressions
Charles age = x+8
Adam age = 5x+8
add their ages and equate them to twice adam's present age 2*5x
x+8+5x+8 = 2*5x
6x+16=10x
4x=16
x=4
x = Charles' age
Adam's age 5x = 5(4) = 20