Given/equations formed from text: I: l=w+3 II: A=l*w III: new area B=(l-2)*w IV: B=A-30
substitute l in II with I to remove l: II': A=l*w= (w+3)*w= w^2+3w
substitute l in III with I to remove l: III': B=(l-2)*w= (w+3-2)*w= (w+1)*w= w^2+w
substitute A and B from II' and III' into IV: B=A-30 w^2+w=w^2+3w-30 30=2w w=15
insert w=15 into I: l=15+3=18 -> A) dimensions of full size rectangle are width 15 and length 18 dimensions of reduced size rectangle are width 15 and length 16
B) full size: 15*18=10*18+5*18=180+90=270cm^2 reduced size: 15*16=10*16+5*16=160+80=240cm^2
