-1 1/2 = -3/2. (-3)*(-3)*(-3)/(2*2*2) = -27/8
2 2/3 = 8/3. 8*8/(3*3) = 64/9
-1 1/7 = -8/7. (-8)*(-8)/ (7*7) = 64/49
(-27) * 64 * 49 / (8 * 9 * 64) = 3*49/8 = 147/8 = 18,375
100%-12%-32%=56%
х-100%
14-56%
х=14*100/56
х=25
в классе 25 человек
(3/7)^(3x+1)=(3/7)^(3-5x)
3x+1=3-5x
3x+5x=3-1
8x=2
x=1/4