Posted by **Joel** on Tuesday, February 22, 2011 at 11:30am.

Select the set of equations that represents the following situation: The cost of eleven CDs and twelve DVDs is $150.62; and the cost of one DVDs and twelve CDs is $116.07. How much do a CD and a DVD cost?

(Points : 3)

11x + 12y = 150.62; 12x + 1y = 116.07

11x • 12y = 150.62; 12x • 1y = 116.07

11x + 12y = 150.62; 1x + 12y = 116.07

11x • 12y = 150.62; 1x • 12y = 116.07

- algebra -
**Henry**, Thursday, February 24, 2011 at 2:52pm
Eq1: 11X + 12Y = 150.62

Eq2: 12X + Y = 116.07

MultiplyEq2 by -12:

11X + 12Y = 150.62

-144X -12Y = -1392.84

Sum: -133X = -1242.22

X = -1242.22 / -133 = $9.34 = Cost of

1 CD.

Substitute 9.34 for X in Eq2:

12*9.34 + Y = 116.07,

112.08 + Y = 116.07,

Y = 116.07 - 112.08 = $3.99 = Cost of 1 DVD.

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