Given the following equations:
x = 3y + 5 (Eq. 1)
-5x + 15y = -25 (Eq. 2)
Let's find the solution using the Substitution Method:
x = 3y + 5 (Substitute to Eq. 2)
-5x + 15y = -25
-5(3y + 5) + 15y = -25
-15y + -25 + 15y = -25
0 - 25 = -25
-25 = -25
It appears that the given system has an infinite number of solutions.
Therefore, the answer is "infinitely many solutions".
