Question 839008
d = number of DVDs
g = number of games
c = number of CDs


d = g + 4 = 3(c + g)
d + c + g = 15


Substitute d into the second equation.


(g + 4) + c + g = 15
c + 2g = 11


3(c + g) + c + g = 15
4c + 4g = 15


Use any method (substitution, elimination) to solve for c or g. We will use substitution: c = 11 - 2g.


4(11 - 2g) + 4g = 15
44 - 8g + 4g = 15
-4g = -29


The solution is not an integer.