<span>А) 90*25+10*25 = 25*(90+10) = 25* 100 = 2500
</span><span>Б) 123*27-23*27 = 27*(123-23) = 27*100 = 2700</span>
X-7,5=9+9x-13,5;
x-9x=3;
-8x=3;
x=-3/8;
(2/3х + 1/8х) * 24 = 38,
16/24х + 3/24х = 38 : 24,
19/24х = 38/24,
х = 38/24 : 19/24,
х = 38/24 * 24/19,
х = 2,
Проверка:
(2/3*2 + 1/8*2) * 24 = 38,
(4/3 + 1/4) * 24 = 38,
(16/12 + 3/12) * 24 = 38,
19/12 * 24 = 38,
19*2 = 380
38 = 38