what is the percentage of C in this substance?

Question

Combustion of 7.51 mg of certain organic compound yields about 17.10 mg CO2 and 5.26 mg of H20. This compound contains only C, H, and O. What is the percentage of C in this substance?

i dont know what im doing wrong, i converted mg to grams and tried solving for the empirical formula of the compound but it didnt seem right

Answer 1

mg of C = 17.10 x 12/44.01 =4.66 mg C
(12/44.01) = the fraction of carbon in CO2
(4.66 x 100)/ 7.51 = 62.05% C

mg of H = 5.26 x 2/18.01 =0.584 mg H
(12/18.01) = the fraction of hydrogen in water.
(0.584 mgH x 100)/7.51 =7.78% H

100 - (%C + %H) = % oxygen