Question

One year ago liz was three times as old as her brother jack. in two years she'll be only twice as old as jack. how old are liz and jack now?

Answer 1

L = liz's age now

J = Jack's age now

L-1 and J-1 are their ages one year ago

L-1=3(J-1)

L-1=3J-3

L=3J-3+1

L=3J-2 (to be used later)

L+2 and J+2 are their ages in two years

L+2=2(J+2)

replace L by 3J-2

3J-2+2=2(J+2)

3J=2J+4

3J-2J=4

J=4 is Jack's age now

L-1=3(J-1)

L-1=3(4-1)

L-1=3*3

L-1=9

L=9+1

L=10 is Liz's age now