Me i usually know how to do this but i idk what i am doing wrong

Tbh i dont really remember how to this this but the only way i could think of solving it is saying how a spuare/rectangle have all equal sides so if they have all equal sides you can divide that number by 4 so 4/30=7.5 so i would say x = 7.5 tell me if its wrong

~ Good Luck :D ~

Area is length x width so:
(x+1)x=30
x^2+x-30=0
(x+6)(x-5)=0
x=-6, or 5. Only +5 makes sense.
So if x=5 then x+1=6 and you see that indeed 5*6=30

It would be 18 cm