Resposta:

A - x=4

B - x=-2

C - x=5

D- x=30

E - x=9

Explicação passo a passo:

A - 30-5x=10 > 30-10=5x > 20=5x > x=20/5 > x=4

B - 5x+5=3x-1 > 5x-3x=-5-1 >2x+-4 > x=-2

C - 4x+10=45-3x > 4x+3x=45-10 > 7x=35 > x=35/7 > x=5

D- x/5 + x/2= 21 mdc > 2x/10+5x/10=21 > 2x+5x/10=21 > 7x/10=21 >

10*7x/10=10*21 > 7x=10*21 > 7x=210 > x=210/7 > x=30

E - 3-2x+6=x-18 > 18+3+6=x+2x > 27=3x > x=27/3 > x=9