3
 = 
1
45
5x

Cross multiply:
3 * 5x = 45 * 1

Simplifying
3 * 5x = 45 * 1

Multiply 3 * 5
15x = 45 * 1

Multiply 45 * 1
15x = 45

Solving
15x = 45

Solving for variable 'x'.

Move all terms containing x to the left, all other terms to the right.

Divide each side by '15'.
x = 3

Simplifying
x = 3