In three year's time, Mr Sullivan will be 3 times as old as his daughter. Six years ago, he was 6 times as old as her. How old are they now?

S=sullivan's age

d=daughter's age

in 3 years time (s+3 and d+3)

sulivan is 3 times as old as daughter

s+3=3 (d+3)

6 years ago (s-6 and d-6)

he was 6 times as old

s-6=6 (d-6)

expand

s+3=3d+9

s-6=6d-36

for 2nd equation, add 6 to both sides

s=6d-30

sub 6d+30 for s in other equation

6d-30+3=3d+9

6d-27=3d+9

minus 3d both sides

3d-27=9

add 27 both sides

3d=36

divide both sides by 3

d=12

sub back

s=6d-30

s=6 (12) - 30

s=72-30

s=42

Mr. Sullivan is 42 now

Daughter is 12 now