The system of equations becomes: s + u = 28 This represent the number of candles sold16s + 10u = 400 This represents the value of the candles sold--------------------- Now all that is left is to solve for s and u. I suggest eliminating one of the two variables. My choice would be eliminating the u terms.
If the question is looking for an absolute value then the answer is 12.
Absolute value |-a| = a.
