How do you calculate the average atomic mass of magnesium, given the following per cent abundances and isotopic masses: 78.99% .^24Mg (23.98504 u), 10.00% .^25Mg (24.98584 u), and 11.01% .^20Mg (25.98259 u)?

The abundance is written as

78.99% of 23.98504 u
10.00% of 24.98584 u
11.01% of 25.98259 u

(0.7899 x 23.98504) + (0.100 x 24.98584) + (0.1101 x 25.98259)

= 24.30505 u