How do you get the answer to 5/8*12/25 by doing cross multiplacation

For cross multiplication, you divide by a number divisible by the number and the number angled across from it. 5 and 25 are both divisible by 5 so you divide both numbers by 5. 5=1 and 25=5. Which temporary makes it 1/8 and 12/5. Since both 8 and 12 are divisible by 4, divide both of them by 4., 8 by 2 times and 12 by 3 times(8=2 and 12=3) So the result is 1/2*3/5 which is 3/10.

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 .