Mass Spectra of Elements Practice Test

A mass spectrum for element W shows two peaks at $m/z=20$ (relative abundance 90) and $m/z=22$ (relative abundance 10). Assuming $+1$ ions, what is the average atomic mass of W?

Element R produces a mass spectrum with peaks at $m/z=78$ (relative abundance 50) and $m/z=80$ (relative abundance 50). Assuming $+1$ ions, what is the average atomic mass of R?