Question 250461
(20-x)(23-x)=20*23-120
460-43x+x^2=460-120
x^2-43x+460-460+120=0
x^2-43x+120=0
(x-40)(x-3)=0
x-3=0
x=3 cm. is the decrease in size of both sides.
Proof:
(20-3)(23-3)=20*23-120
17*20=460-120
340=340