Пошаговое объяснение:
1)
10/(x-6)=2/3
2*(x - 6) = 10*3
2x - 12 = 30
2x = 30+12
2x = 42
x = 42 : 2
x = 21
2)
3/4=6/(5-x)
3*(5 - x) = 6*4
15 - 3x = 24
3x = 15 - 24
3x = -9
x = -9 : 3
x = -3
