Решение:
1) $4x - 9x = (4 - 9)x = -5x$
2) $-19t + 2t = (-19 + 2)t = -17t$
3) $-7h + 12h = (-7 + 12)h = 5h$
4) $13d - 24d = (13 - 24)d = -11d$
Ответы:
1) $4x - 9x = (-5)x = -5x$
2) $-19t + 2t = (-17)t = -17t$
3) $-7h + 12h = (5)h = 5h$
4) $13d - 24d = (-11)d = -11d$
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