Question

Вычисли УДОБНЫМ способом:
$15 times 3 + 15 times 4 + 15 times 5 - 16 times 3 - 16 times 4 - 16 times 5$
$25 times ( - 3) + 25 times ( - 4) + 25 times ( - 5) + 25 times 6 + 25 times 7$
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Answer 1

$=15(3+4+5)-16(3+4)+25(3-4-5+6)=15*12-16*7+25*0=180-112=68$