No mathematics the most common way of solving an equation will be PEMDAS so the answer for your question will most likely be subtraction.
Answer: 15.0 moles of
are formed from 30.0 mol of 
Explanation:
The balanced chemical reaction is :
According to stoichiometry :
2 moles of
give = 1 mole of 
Thus 30.0 moles of
will give =
of 
Thus 15.0 moles of
are formed from 30.0 mol of 
Answer: 462 g
Explanation:molar mass is M= 63.55 +2·(12.01+14.01)= 115.59 g/mol.
Mass m= n·M = 4.0 mol·115.59 g/mol= 462.36 g
we can differentiate a heterozygous individual from a homozygote by analyzing their alleles. If the alleles in the homologous chromosomes are the same, we say that it is a homozygote. If the alleles are different, the individual is heterozygous.