Formula for area of rectangle: A=L x w Here A=85 square ft Length, L=w+12
Put values in formula. 85=(w+12)w 85=w^2+12w Subtract 85 from both sides w^2+12w-85=0 Factorise the equation. (w-5)(w+17)=0 w=5 and w=-17 Ignore the negative value of width. Width, w= 5 ft and Length, L=12+5=17 ft