Question 210974
The present area is:
{{{A = 40*20}}}sq.m.
{{{A = 800}}}sq.m. If you add x to the width and this doubles the area, you have:
{{{1600 = 40(20+x)}}} Divide both sides by 40.
{{{40 = 20+x}}} Subtract 20 from both sides.
{{{20 = x}}}
The sides must be extended by 20 meters.