Answer: 50/4 or 12.5
Explanation:
We can cross-multiply in this situation.
Cross-multiplying...

8n = 10(10) = 100
In other words, we multiply the denominator of 10/8, which is 8, by the numerator of n/10, which is n, and vice-versa.
Dividing 8 on both sides....
n = 100/8 = 50/4 = 12.5