Răspuns:
a). (x+4)×3=5x. 5x-3x=12. 2x=12. x=6
b). 10x-10=3. 10x=13. x=13/10
c)100x+200=25x. 75x=-200. x=-8/3
d). 75×8×2=40x. 30=40x. x=3/4
e).115/25=(10x+45)/(10x-45)=100x^2-45^2
23/5+45^2=100x^2
=100x^2
x=√(2025+23/5)/10
f). x/3=10/3-5x/3. 6x=10 x=5/3