Find all solutions by factoring. \[ 4 a^{2}-17 a=15 \]

Step 1 ：Rearrange the equation into a standard quadratic equation form: \(4a^2 - 17a - 15 = 0\).

Step 2 ：Find all solutions by factoring.

Step 3 ：The solutions to the equation are \(a = -\frac{3}{4}\) and \(a = 5\).

Step 4 ：Final Answer: The solutions to the equation are \(\boxed{-\frac{3}{4}}\) and \(\boxed{5}\).