Please help me and tell me the work with the answer please and thank you.

Answer:
x=15
Step-by-step explanation:
Because the two triangles are similar, the lengths of corresponding sides are proportional.
For example, 12 is to x as 4 is to 5:
12 4
------ = ----- Solve this equation of ratios.
x 5
Cross multiplying results in 4x = 60, so that x = 15.