You don't cross-multiply when you're multiplying fractions.
Multiplying fractions is really simple:
-- The numerator of the product is the product of the two numerators.
The two numerators are 5 and 12, so the numerator of the product is 60 .
-- The denominator of the product is the product of the two denominators.
The two denominators are 8 and 25, so the new denominator is 200.
The new fraction is 60/200 .
You could simplify it, and then it would look like 3/10 .