Answer:
$39.00
Explanation:
Let x = cost of backpack. Then
0.30 x = discount, and
x - 0.30x = sale price
x - 0.30x = 27.30
Combine like terms
0.70x = 27.30
Divide each side by 0.70
x = $39.00
The original price of the backpack was $39.00.
Check:
Original cost = $39.00
Less 30 % = -11.70
Sale price = $27.30