Multiply

8x^3/5 * 10/x^7
8/5*10/x^4
8*2/x^4
16/x^4

Is this correct ?

yes.

Yes, your simplification is correct. To explain the steps to get this answer:

Step 1:
Start by multiplying the coefficients (numbers) separately and write the result as the numerator:
8 * 10 = 80

Step 2:
Next, multiply the variables with the same base, in this case, the "x" terms:
x^3 * x^(-7) = x^(3+(-7)) = x^(-4)

Step 3:
Combine the result from step 1 and step 2 to get the fraction:
80/x^4

Therefore, your simplification is correct: 16/x^4.