The compound adrenaline contains 56.79% C, 6.56%H, 8.28% N, and 28.37% O by mass. Assuming 100 g of adrenaline, how many moles of carbon are present?

well since there are 100 grams, those percentts are the grams of each element

now for example for C :
C has about 12 grams/mol
56.79 grams / 12 grams/mol = 4.7 mols of C