Variable $x$ cannot be equal to $0$ since division by zero is not defined. Multiply both sides of the equation by $2x$, the least common multiple of $x,2$.
$$2\times 45=x\left(7\times 2+1\right)$$
Multiply $2$ and $45$ to get $90$.
$$90=x\left(7\times 2+1\right)$$
Multiply $7$ and $2$ to get $14$.
$$90=x\left(14+1\right)$$
Add $14$ and $1$ to get $15$.
$$90=x\times 15$$
Swap sides so that all variable terms are on the left hand side.
