Answer: $312.5
Explanation:
Lily spent one-fifth of her salary on a pair of shoes and then got $90 as a birthday present from her mom and was left with $340. To calculate the amount Lily had at first goes thus:
Since Lily spent 1/5 on shoes, that means she had (1 - 1/5) = 4/5 left.
Let the amount she had at first be y.
(4/5 of y) + 90 = 340
(4/5 × y) + 90 = 340
0.8y + 90 = 340
0.8y = 340 - 90
0.8y = 250
Divide both side by 0.8
0.8y/0.8 = 250/0.8
y= 312.5
She had $312.5 at first.