1) (780-m*60) : 6=70 2) 640: (x*9+8) = 8

1) (780 - m * 60) : 6 = 70,

780 - m * 60 = 70 * 6,

780 - m * 60 = 420,

m * 60 = 780 - 420,

m * 60 = 360,

m = 360 : 60,

m = 6.

Ответ: 6.

2) 640 : (x * 9 + 8) = 8,

x * 9 + 8 = 640 : 8,

x * 9 + 8 = 80,

x * 9 = 80 - 8,

x * 9 = 72,

x = 72 : 9,

x = 8.

Ответ: 8.