Answer:
x = 5
Step-by-step explanation:
Because the red-marked lines are parallel, we know that the ratios are the same
5x : 45 = 20 : 36
5x/45 = 20/36
5x * 36 = 20 * 45
5x * 4 = 20 * 5
5x * 1 = 5 * 5
