Gail and her brother Henry had a combined age of 47. If Gail was twice as old as Henry ten years ago, how old is Gail today?

2 answers

g+h = 47
g-10 = 2(h-10)
g = 28
g+h = 47
g-10 = 2(h-10)
g-10=2h-20
g=2h-10
Therefore g+h=47 is the same as 2h-10+h=47.
So 2h-10+h=47
3h=57
h=57/3=19
Then g+19=47
g=47-19=28yrs :)