Odpowiedź:
zad 1
a) x + y = 5 + 20 = 25
b) y - x = 20 - 5 = 15
c) xy = 5 * 20 = 100
d) 2x + 3y = 2 * 5 + 3 * 20 = 10 + 60 = 70
e) 2y - 3x = 2 * 20 - 3 * 5 = 40 - 15 = 25
zad 2
a) 2x + 4x + x = 7x
b) 2x + 7y + 4x + 3y = 6x + 10y
c) 5x + 9y - x - 2y = 4x + 7y
d) 2a + 5b - 2a - b = 4b
e) 10a + 10b - a - 3b = 9a + 7b