A DVD costs twice as much as a music CD. Jack buys 2 DVDs and 2 CDs and spends $45. Determine how much one CD costs, in dollars. [Only an alegbraic solution can receive full credit]
Let [tex]d=[/tex] the cost of a DVD Let [tex]c=[/tex] the cost of a CD
We have [tex]d=2c[/tex] and [tex]2d+2c=45[/tex]
We can replace [tex]d[/tex] with [tex]2c[/tex] in the second equation and get [tex]2(2c)+2c=45[/tex] [tex]\rightarrow 4c+2c=45[/tex] [tex]\rightarrow 6c=45[/tex] [tex]\rightarrow c=7.5\rightarrow\$7.50[/tex]
