Ответ:
Пошаговое объяснение:
7x + 2x = (7+2)*x = 9x
11y - 3y = (11-3)*y = 8y
9a + 6a = (9+6)*a = 15a
13c - 3c = (13-3)*c = 10c
3x*5*10 = (3*5*10)*x = 150x
4*2y*15 = (4*2*15)*y = 120y
70*50y*2 = (70*50*2)*y = 7000y
6a*300*500 = (6*300*500)*a = 900000a