calculate the difference between the molecular formula and molecular masses for..

a. CH3OH and C2H5OH

b. C2H5OH and C3H7OH

PLEASE PLEASE ANSWER FAST!!! I NEED IT KNOW!!!!!

c. C3H7OH and C4H9OH

a. CH₃OH and C₂H₅OH

b. C₂H₅OH and C₃H₇OH

c. C₃H₇OH and C₄H₉OH

In all the given pairs of compounds, the molecular formula of the first compound differs from the second by a -CH₂ unit.
Mass of CH₂ = 12 + 2 x1 = 14 u
So, the difference in molecular mass of the compounds in each pair is 14u