Answer :
5.5 x 7.5 = 41.25 , 5.5 x (x) = 5.5x the expression is now 41.25 + 5.5x
41.25 represents the original size of mural in square ft
5.5x represents the extension of the mural
41.25 represents the original size of mural in square ft
5.5x represents the extension of the mural