Answer:
x = 7.5
Explanation:
This is a right angle triangle so the Pythagorean rule applies
The hypotenuse is opposite the right angle and it is also the longest side
Now, apply the Pythagorean rule
15^2 = 13^2 + x^2
225 = 169 + x^2
225 - 169 = x^2
56 = x^2
Take the square root of both sides
7.48 = x
x = 7.5 .........to the nearest tenth