# What is the percent composition of Carbon in aspartame C_14H_18N_2O_5, an artificial sweetener?

Aspartame has a formula of ${C}_{14} {H}_{18} {N}_{2} {O}_{5}$. This gives a formula mass of $294.31 \cdot g \cdot m o l$. Note that you really should have included these details in your question.
$\text{% composition of carbon}$ $=$ $\frac{14 \times 12.011 \cdot g \cdot m o {l}^{-} 1}{294.31 \cdot g \cdot m o {l}^{-} 1}$ xx100% $=$ ??%