Question

#4) mary, who is sixteen years old, is four times as old as her brother. how old will mary be when she is twice as old as her brother?

Answer 1

Hi! Tricky question you've got there!

So far, we know that Mary is 16 and her brother is 4 (16 is 4 times as old as 4).

16 + x = 2(4 + x)

16 + x = 8 + 2x

x = 8

Now, this isn't finished yet.


(4 + 8) = 12

12 twice is 24, so Mary will be 24 years old.