Question 170636
20*23=460cm^2 is the original area.
(20-x)(23-x)=460-120
460-43x+x^2=340
x^2-43x+460-340=0
x^2-43x+120=0
(x-40)(x-3)=0
x-3=0
x=3 
Thus the new dimentions are:
20-3=17
23-3=20
Proof:
17*20=460-120
340=340