x+y=52
2/3x+3/4y=37
![\left \{ {{x+y=52} \atop {\frac{2}{3}x +\frac{3}{4}y =37}} \right. \\\\y=52-x\\\\\frac{2}{3}x+ \frac{3}{4}(52-x)=37\\ \\\frac{2}{3}x+39- \frac{3}{4} x=37\\\\\frac{2}{3}x- \frac{3}{4}x=-2\\ \\\frac{8}{12}x- \frac{9}{12}x= \frac{-24}{12}\\\\\frac{-1}{12}x= \frac{-24}{12}\\ \\x=24](https://tex.z-dn.net/?f=%5Cleft+%5C%7B+%7B%7Bx%2By%3D52%7D+%5Catop+%7B%5Cfrac%7B2%7D%7B3%7Dx+%2B%5Cfrac%7B3%7D%7B4%7Dy+%3D37%7D%7D+%5Cright.+%5C%5C%5C%5Cy%3D52-x%5C%5C%5C%5C%5Cfrac%7B2%7D%7B3%7Dx%2B+%5Cfrac%7B3%7D%7B4%7D%2852-x%29%3D37%5C%5C+%5C%5C%5Cfrac%7B2%7D%7B3%7Dx%2B39-+%5Cfrac%7B3%7D%7B4%7D+x%3D37%5C%5C%5C%5C%5Cfrac%7B2%7D%7B3%7Dx-+%5Cfrac%7B3%7D%7B4%7Dx%3D-2%5C%5C+%5C%5C%5Cfrac%7B8%7D%7B12%7Dx-+%5Cfrac%7B9%7D%7B12%7Dx%3D+%5Cfrac%7B-24%7D%7B12%7D%5C%5C%5C%5C%5Cfrac%7B-1%7D%7B12%7Dx%3D+%5Cfrac%7B-24%7D%7B12%7D%5C%5C+%C2%A0%5C%5Cx%3D24)
24 учеников в 8а классе
52-24=28 учеников в 8б классе
Проверка
8+7=15 пошли в музей современного творчества
52-15=37 пошли в музей космонавтики
Ответ:28 учеников
(x + 3)(x - 4)(x - 6) < 0
x ∈ (-∞; -3)∪(4; 6)
Решение:
3x+y=1 3x+y=1 9x+3y=3
5x+5-3y=30 5x-3y=25 5x-3y=25
14x=28 x=2 y=1-3x=1-6=-5
x=-5/3+1=-2/3
8b-27=5
8b=5+27
8b=32
b=32:8
b=4