Line Plots · Challenge problem

A line plot shows lengths of ribbon, in inches. Rosa moves every X that was above $\dfrac{3}{8}$ to $\dfrac{5}{8}$ (each of those ribbons is replaced by a longer one). Nothing else changes. The total length of all the ribbons goes up by $1\dfrac{1}{2}$ inches. How many X's were above $\dfrac{3}{8}$?