The ratio of carbon atoms to hydrogen atoms to oxygen atoms in a molecule of dicyclohexyl maleate is 4 to 6 to 1. what is its molecular formula if its molar mass is 280 g?

Knowing the ratio between atoms we can write an empirical formula: 

C4H6O 

we compute the molar mass of this single formula: 
4x12 + 6 x 1 + 16 x1 = 70 g / mol 

Now, as we know the actual molar mas being 280 g/mol, we divide this number by 70 and we get the ratio between empirical formula and molecular actual formula: 

280 / 70 = 4 

This means that actual molecular formula is: 

(C4H6O)4 or 

C16H24O4