(20+x) x (30+x)-600=1000
600+20x+30x+x^2-600=1000
the 600's cancel out
20x+30x+x^2=1000
50x+x^2=1000
50x/50+x^2=1000/50
x^2=20
sqrt x^2=sqrt 20
x=4.4721
x=4.5(approx)
600+20x+30x+x^2-600=1000
the 600's cancel out
20x+30x+x^2=1000
50x+x^2=1000
50x/50+x^2=1000/50
x^2=20
sqrt x^2=sqrt 20
x=4.4721
x=4.5(approx)