First of all you need a balanced equation:
2(C4H10) + 11(O2) ---> 10 (H2O) +8 (CO2)
Then, you convert the unit :
[tex]7.14 g C4H10[/tex] x [tex] \frac{1mole C4H10}{58gC4H10} [/tex]×[tex] \frac{10mole H2O}{2mole C4H10} [/tex]×[tex] \frac{18g H2O}{1moleH2O} [/tex]
The answer should be 11.1g
( I'm not 100% sure about it though)