<u>80</u>÷1*4 или же 80÷4*1
(279+х)+52=560
х=560-52=508-279=229
x=229
(279+229)+52=560
1) 5y - 72 = 48 - 3y
5y + 3y = 48 + 72
8y = 120
y = 120 : 8 = 15
2) 53(x - 961) = 3975
x - 961 = 3975 : 53
x - 961 = 75
x = 75 + 961 = 1036
3) (k + 2958) : 87 = 134
k + 2958 = 134 * 87
k + 2958 = 11 658
k = 11 658 - 2 958 = 8 700
4) 69 + 4m = 2m + 153
4m - 2m = 153 - 69
2m = 84
m = 84 : 2 = 42