Solution: Let $ x $ be the total GB used. The cost equation is $ 12 \times 20 + 0.08(x - 20) = 38.40 $. Simplify: $ 240 + 0.08x - 1.6 = 38.40 $. Combine terms: $ 238.4 + 0.08x = 38.40 $. Subtract 238.4: $ 0.08x = -199.6 $. Divide by 0.08: $ x = -2487.5 $. This negative value indicates an inconsistency, suggesting the business used fewer than 20 GB. Recalculate without the \$0.08 overage: $ 12x = 38.40 $ → $ x = 3.2 $. Verify: \$12 × 3.2 = \$38.40. Final answer: $ \boxed3.2 $ GB. - Appfinity Technologies