h worked the following problem incorrectly.

Part 1) In which line was the mistake made?
Part 2) Show your work and give the correct answer?

Line 1 40 ÷ 5(3 − 1) − 4
Line 2 40 ÷ 5(2) − 4
Line 3 40 ÷ 10 − 4
Line 4 4 − 4
Line 5 0