When multiplying fractions you just multiply the numerators together:
3X5 = 15
Then you multiply the denominators together:
10X12 = 120
So 15/120. Now simplify
Divide both by 15
1/8
I chose 15 because I knew that off the top of my head. If you didn't know that start with what you do know. For example
15/120 - you can divide by 5
3/24 - you can divide by 3
1/8
You still get the same answer. If you notice dividing by 5 and then by 3 is the same as dividing by 15
