Area of rectangle = length x width
therefore
280 feet squared = 7 x 3x + 10
280 = 7(3x+10)
280 = 21x + 30
if you take 30 from both sides, then:
250 = 21x
then to find x you divide both sides by 21.
21x/21 = x, and 250/21 = 11.09 (rounded to 2 decimal places)
therefore x = 11.09.
Then to find the dimensions, we already know that the width = 7 because it is written on the diagram. So we substitute x into the length.
3x + 10
=3(11.09) + 10
=33.27 + 10
=43.27.
Therefore, the dimensions are length = 43.27 feet, width = 7 feet
