(к+2958)687=134
К+2958=134*87
К+2958=11658
К=11658-2958
К=8700
ПРОВЕРКА (8700+2958):87=134
1) 2-2-2=-2
2)5-5=0
3)7+2=9
4)6-6=0
7)8+3=11
874.1
4x+5(3-2x) = 5-11x
4x+15-10x = 5-11x
-6x+11x = 5-15
5x = -10
x = -10:5
x = -2
Ответ: -2
874.3
8x+3(7-2x) = 4x+3
8x+21-6x = 4x+3
2x-4x = 3-21
-2x = -18
x = -18:(-2)
x = 9
Ответ: 9
875.2
5+(7x-12)/3 = x+13
15+7x-12 = 3x+39
7x-3x = 39-3
4x = 36
x = 36:4
x = 9
Ответ: 9
876.1
8y-3(2y-3) = 7y-2(5y+8)
8y-6y+9 = 7y-10y-16
2y+3y = -16-9
5y = -25
y = -25:5
y = -5
Ответ: -5
876.3
5y+7(3-y) = 3(5-2y)-6
5y+21-7y = 15-6y-6
-2y+6y = 9-21
4y = -12
y = -12:4
y = -3
Ответ: -3
877.1
5(3-2y)-4(9-y) = 3(y+5)
15-10y-36+4y = 3y+15
-6y-3y = 15+21
-9y = 36
y = 36:(-9)
y = -4
Ответ: -4