Răspuns:
e)18:[(5²-5x)×2-11]=2
18:[(25-5x)×2-11]=2
18:(50-10x-11)=2
18:(39-10x)=2
18/(39-10x)=2
18=2(39-10x)
9=39-10x
10x=39-9
10x=30
x=30:10
x=3