the question says :
Two elements, A and B, combine to form two binary compounds. In the first compound, 3.5 g of A combines with 8.00 g of B. In the second compound, 5.0 g of A combines with 17.1 g of B. If the formula of the first compound is AB2, then the formula of the second compound would be ?
I can't even make the first step :(