Okay, so I have this reduction formulae question

Establish a reduction formula to find I_{m,n}=∫cos^{m}x . sin^{n}x dx

Prove that (m+n). I_{m,n}= (m-1) . I_{m-2,n }And okay I solve the problem above, but then the question says

evaluate I_{5,6 }and I can't find the value 8/693 which is the answer in answer key. I'm so confused, what I need to do is just substituting the value right?

But the problem is the I is the integral of ∫cos^{m}x . sin^{n}x dx so what to do with x, do we just put whatever on x, or what?

Please help me ! thanks