When determining the formula for aacompound, it is important to know valence numbers of each element. Suppose that element A has a valence number of...

When determining the formula for aacompound, it is important to know valence numbers of each element. Suppose that element A has a valence number of 3 and element B has a valence number 2. If the two elements combine, then when writing the formula for the resulting compound what subscript number will be given to the element B. would it be 1, 2, 3 or 5?I think the answer is 3 so it would be B3