Answer:
a= 20
Step-by-step explanation:
We can use the Pythagorean theorem to solve
a^2+b^2 = c^2 where a and b are the legs and c is the hypotenuse
The diagonal is the hypotenuse and the length and width are the legs
a^2 + 15^2 =25^2
a^2 +225 = 625
Subtract 225 from each side
a^2+225-255=625-225
a^2 = 400
Take the square root of each side
sqrt(a^2) =sqrt(400)
a = 20
