It is necessary without changing the position of the numbers 1 2 3 4 5 using mathematical signs to get 40 and 80

(1 – 2 + 3 + 4) * 5 = 40
First action: one minus two equals one
1 – 2 = 1
Second action: one plus three equals four
1 + 3 = 4
Third action: four plus four equals eight
4 + 4 = 8
Fourth act: eight times five equals forty
8 * 5 = 40

(1 – 2 + 3) * (4 * 5) = 80
First action: one minus two equals one
1 – 2 = 1
Second action: one plus three equals four
1 + 3 = 4
Third action: four times five equals twenty
4 * 5 = 20
Fourth action: four times twenty equals eighty
4 * 20 = 80