How would i determine the mass of the other Isotope PLEASE HELP

Sep 2015
7
0
Silver has two naturally occurring isotopes. The first, with a mass of 106.9 amu, has a natural abundance of 51.85%. Given its atomic weight of 107.9 amu, determine the mass of the other isotope.

I know the answer is 109.0 amu. But how do you get it.

Please Help...