12x-35+7x=98
19x=133
x=7
_____________
25(x+1)-16=59
25x=50
x=2
_____________
13(x+6)-72=123
13x=117
x=9
_______________
77+8(x-5)=125
8x=88
x=11
6/15 = 6*6 / 15*6 = 36/90 и 11/18 = 11*5 / 18*5 = 55/90
4/15 = 4*4 / 15*4 = 16/60 и 3/20 = 3*3 / 20*3 = 9/60
2/77 = 2*4 / 77*4 = 8/308 и 3/44 = 3*7 / 44*7 = 21/308
4/49 = 4*9 / 49*9 = 36/441 и 5/63 = 5*7 / 63*7 = 35/441