d) 17/23·x=92
x=92:17/23=92·23/17
e)23/6·x=54
x=54:23/6=54·6/23=324/23
f)31/12·x=96
x=96:31/12=96·12/31=1152/31
g)x/(x+1) · 12=8
12x/(x+1)=8
12x=8(x+1)
12x=8x+8
12x-8x=8
4x=8
x=8:4=2
h)(3x+1)/(2x+5) · 252=20
252(3x+1)=20(2x+5)
756x+252=40x+100
756x-40x=100-252
716x=-152
x=-152/716=-76/358=-38/179
i) x/3 · (x+1)=4
x(x+1)=3·4 → x=3