Answer:
$12.50
Explanation:
Let Ricardo received the allowance = x dollars.
He spent half of her allowance on a new paper back book
so amount left with him = x -

=

then he bought a snack with the amount = $1.25
amount left = (
- 1.25)
When he reached home amount with him = $5.00
Therefore,
-1.25 = 5
= (5 + 1.25)
= 6.25
x = 2 × 6.25
x = $12.50
Ricardo received allowances = $12.50