Martina went shopping. She spent a fifth of what she had in her wallet and then a fifth of what remained. In all, she spent $36. How much did she start with?
x is th amount she starts with in her wallet.
she spends 1/5 of x 1/5 x so now she has 4/5x LEFT
of what she has LEFT , she spends 1/5
1/5 * 4/5x
so all totalled she spent 1/5x + 1/5 * 4/5 x =36
1/5x + 4/25x =36
5/25 x + 4/25 x = 36
9/25 x = 36
x =36 (25/9) = original amount = $100.