Answer:
b=4
Explanation:
The side opposite the right angle is the hypotenuse. The sides touching the right angle are the legs
Since this is right triangle we can use the Pythagorean theorem
a^2+b^2 = c^2 where a and b are the legs and c is the hypotenuse
3^2+b^2 = 5^2
9+b^2 = 25
Subtract 9 from each side
9-9+b^2 = 25-9
b^2 =16
Take the square root of each side
sqrt(b^2) = sqrt(16)
b=4