Ashley had 1/3 as many baseball cards as Hunter. Hunter gave 7 baseball cards to Ashley so that they would each have the same amount. How many baseball cards did the two friends have altogether?
number for Hunter --- 3x
Ashley ---- x , (nice way to avoid fractions)
after the exchange:
Hunter has 3x - 7
Ashley has x + 7
they are equal, so ....
3x - 7 = x + 7
clean it up