Answer:
Her remaining dollars are 28.
Explanation:
Consider the provided information.
Sandy has 10 dollars in her collection.
She gave 3 to her younger sister.
Remaining dollars are:
$10 - $3 = $7
Her parents were so impressed that they quadrupled (left multiplied by 4).
So $7 × 4 = $28
The expression can be 7 × 4 = x.
Hence she left with $28.