A bag of bread rolls costs x dollars
A loaf of multigrain bread cost two dollars more than a bag of bread rolls = x + 2
Let the number of loaves of multigrain loaves Mr Lopez bought be n, then
n(x + 2) = 50
n = 50 / (x + 2)
Therefore, the number of loaves of bread he buys is given by n = 50 / (x + 2).