3n/5 - 6 = 0 (-3n/5 is a fraction for anyone who's ? ?

Can someone me out here number 4 plz

Find the nonpermissible replacement for binthis expression.b2/5b +5

A)a square brown tarp has a square green patch green in the corner the side length of the tarp is (x + 8) and the side length of the patch is x what is the area of the brown part of the tarpb)a square red placemat has a gold square in the corner the side length of the gold square is (x - 2) inches with the width of the red region is 4 in what is the area of the red part of the placemat