Answer:
x=8
Step-by-step explanation:
Given two triangles are similar
When two triangles are similar , then the length of two similar triangles are always  proportional.
The length of the corresponding sides are proportional
Ratio of hypotenuse = Ratio of the base
[tex]\frac{20}{10} = \frac{x}{4}[/tex]
Now we solve for x
Cross multiply the fractions
4 * 20 = x* 10
80 = 10x
Divide by 10 on both sides
x= 8
