I need help with chem homework. I put the full question below

Question

The complete and balanced reaction for the combustion of octane is shown below.

2 C₈H₁₈ (l)  +  25 O₂ (g)  -->  16 CO₂ (g)  +  18 H₂O (g)

You have been assigned a mass of octane, look on excel to get that mass and enter it here________123____________g  2 points   

Then determine how many grams of carbon dioxide will form if all your octane reacts. (SHOW ALL WORK!!)  

Answer 1

2 C₈H₁₈ (l) + 25 O₂ (g) -->  16 CO₂ (g)  +  18 H₂O (g) ... balanced equation

Molar mass C₈H₁₈ = 114 g / mol

Molar mass CO₂ = 44 g / mol

moles C₈H₁₈ combusted = 123 g x 1 mol / 114 g = 1.079 moles

moles CO₂ formed = 1.079 mols C₈H₁₈ x 16 mols CO₂ / 2 mols C₈H₁₈ = 8.632 mols CO₂

mass CO₂ formed = 8.632 mols CO₂ x 44 g CO₂ /mol = 380. g CO₂ (3 sig. figs.)