First convert your mixed numbers to improper fractions.
You do this by multiplying the denominator and the whole number, and then adding the numerator. The denominator remains the same though.
5 3/4 becomes 23/4
2 1/2 becomes 5/2
23/4 x 5/2
When multiplying fractions, just multiply straight across.
23 x 5 = 115
4 x 2 = 8
115/8 is the answer.
Or in mixed number form, divide 115 by 8 and you get
14 3/8