we know that
the area of the rectangle is equal to
[tex]A=L*W[/tex]
where
L is the length side of the rectangle
W is the width side of the rectangle
In this problem we have
[tex]L=(5x-3)\ units\\W=(x+7)\ units[/tex]
substitute the values in the formula above to find the area
[tex]A=(5x-3)*(x+7)[/tex]
[tex]A=(5x-3)*(x+7)\\A=5x*x+5x*7-3x-3*7\\A=5x^{2}+35x-3x-21\\A=5x^{2}+32x-21[/tex]
therefore
the answer is the option
5x2 + 32x − 21
