Check for values greater than zero in 2 cells

[spartacus_33]

I can"t seem to remember how to compare 2 cells before doing a calculation. Please Help:

Let's say I want to divide the numbers from 2 cells, down a long column. Let's further say that in some instances there aren't any numbers in either of the cells. You get a divide by zero error.

So you have values in a1 and b1 through a10 and b10. You want to divide the value in the a column by the value in the b column and return the answer in the adjacent c column. You've copied the formula all the way down to c20.

All the cells from c11 to c20 will have divide by zero errors.

What is the syntax to check if both cells in columns a and b are greater than zero so that either an answer will be returned or just a blank cell will result, (when nothing is in one of the cells from a or b?

The following formula works for checking the status of cell A, how do I also check the value in cell B?
=(IF(A5>0,A5/B5,""))

something like?:
=(IF(A5>0 and B5>0,A5/B5,""))