Respuesta :

irspow
Let c and d be the number of cds and dvds respectively.

c+d=12

c=12-d

The we are told that:

2c+3d=31, using c found above in this equation gives you:

2(12-d)+3d=31

24-2d+3d=31  

24+d=31

d=7

So Phillip bought 7 dvds.

check...

3*7+2(12-7)=31

21+2(5)=31

21+10=31

31=31
zame

Answer:

he bought 7 dvds

Step-by-step explanation:

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