Answer:
n = 10
Step-by-step explanation:
In this geometry, all of the right triangles are similar. That means corresponding sides are proportional.
short side / long side = n/20 = 5/n
n² = 20·5 = 100 . . . multiply by 20n
n = 10 . . . . . . . . . . . take the square root
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Additional comment
The ratio of hypotenuse to short side is also proportional:
m/5 = (20+5)/m
m² = 125 . . . . . multiply by 5m
m = 5√5 . . . . . take the square root
