How would I solve this:

Question

The atomic mass of 6/3Li and 7/3Li are 6.0151 amu and 7.0160 amu, respectively. Calculate the natural abundances of these 2 isotopes. The average atomic mass of Li is 6.941.

All I know is how to get the atomic mass and not the natural abundances.

Answer 1

I figured it out

Answer 2

Let a= the percent of 6/3 Li
let b= the percent of 7/3li

a + b = 100
6.0151a + 7.0160b = 6.941(100)

now solve like simultaneous equations in algebra