Bill is now 100% older then his younger sister Rebecca
In 8 years he will be 20% older
How old is Rebecca now?
Rebecca's age = x Bill's age = 2x 2x + 8 = 1.2(x+8)
.8x = 1.6
x = 1.6/.8=2 Bill is 4 Rebecca is 2
100% older means twice as old
20% older means 6/5 as old
Let Rebecca's current age = x so....Bill's = 2x
In 8 years we have........his age = 6/5 her age
2x + 8 = (6/5) [ x + 8] simplify
2x + 8 = (6/5)x + 48/5
2x + 8 = (6/5)x + 48/5 subtract 8, (6/5)x from both sides
2x - (6/5)x = 48/5 - 8
(4/5)x = 8/5 multiply through by 5
4x = 8 divide both sides by 4
x = 2 this is Rebecca's current age.......so Bill = 2x =4
And...in 8 years, Rebecca will be 10 and Bill will be 12 .....and 12 is 6/5 of 10 → 20% more than 10