Answer:
19.2
Step-by-step explanation:
Okay, so if we slice this rectangle in half along the diagonal, we see that we can use the Pythagorean Theorem, a^2+b^2=c^2 to find the length of the diagonal. 12^2+15^2=369. The square root of 396 is 19.20937... rounded to the tenths is 19.2.
