Express $\frac{3x}{3}$3x3 in simplest form.
Express $\frac{8x}{16}$8x16 in simplest form:
Simplify the expression $\frac{4u^3}{9u^3}$4u39u3.
Simplify the expression $\frac{-20m}{4m}$−20m4m.
Simplify rational expressions by adding, subtracting, multiplying, and dividing, and state the restrictions on the variable values