Let us first find how much he is spending every year, to do this let's find his monthly expense and multiply it by 12.
Every month Cameron spends 1040 + 980 + 120 = 2140
To find out how much he spends yearly, multiply the monthly value by 12,
2140 x 12 = 25680
This value is more than his net income so he clearly has a surplus, but to check we can subtract 129 from every month to get:
(1040 + 980 + 120 - 129) = 2011
2011 x 12 = 24132, which shows that his budget is saving 129 surplus every month. Choice B is correct.
144 is a square of 12
Hope this helps!
