proszę na jutro oblicz wartości wyrażeń algebraicznych

7x - 1 = 7 * 3 - 1 = 21 - 1 = 20
5y + 3x = 5 * 0 + 3 * 4 = 0 + 12 = 12
-a + 5b = -4 + 5 * 2 = -4 + 10 = 6
9(x - 1) = 9 * (-3 - 1) = 9 * (-4) = -36
x + y = -9 + 2 = -7
(x - 8)/2 = (10 - 8)/2 = 2/2 = 1