Help!!!!!!!!!!!!! chem idiot ?

Question

The element europium exists in nature as two isotopes: 151Eu has a mass of 150.9196 amu, and 153Eu has a mass of 152.9209 amu. The average atomic mass of europium is 151.96 amu. Calculate the relative abundance of the two europium isotopes.

Answer 1

150.9196 / 151.96 = 0.9932. = 99.32% of 151Eu.

Therefore, 153Eu = 0.68%.

Answer 2

150.9196X + 152.9209(1-X) = 151.96

151Eu has an abundance of 48%, thus 153Eu has an abundance of 52%.