Variable $z$ cannot be equal to $-15$ since division by zero is not defined. Multiply both sides of the equation by $9\left(z+15\right)$, the least common multiple of $z+15,9$.
$$9\times 2=4\left(z+15\right)$$
Multiply $9$ and $2$ to get $18$.
$$18=4\left(z+15\right)$$
Use the distributive property to multiply $4$ by $z+15$.
$$18=4z+60$$
Swap sides so that all variable terms are on the left hand side.
$$4z+60=18$$
Subtract $60$ from both sides.
$$4z=18-60$$
Subtract $60$ from $18$ to get $-42$.
$$4z=-42$$
Divide both sides by $4$.
$$z=\frac{-42}{4}$$
Reduce the fraction $\frac{-42}{4}$ to lowest terms by extracting and canceling out $2$.
