Homework Help: math

Posted by Tory Smith on Saturday, January 15, 2011 at 5:33pm.

The cost of thirteen CDs and seven DVDs is $99.80; and the cost of seven DVDs and twelve CDs is $84.11.

math - helper, Saturday, January 15, 2011 at 5:52pm
want do you need to find?

this problem is not complete
math - Jen, Saturday, January 15, 2011 at 5:55pm
13c+7d=99.8
12c+7d=84.11
Multiply the 2nd equation by -1
13c+7d=99.8
-12c-7d=-84.11
c=
Plug that back into either original equation to solve for d.

Related Questions

math - for every 8cds sold, there were 12 dvds sold. a combined total of 70 cds ...
Math - Natalie has 138 DVDs and 419 CDs. If you were to estimate the sum of the ...
Math - Write and equation to match the problem situation below. Callie has 4 ...
Math - Natalie has 138 dvds and 419 cds. If you were to estimate the sum of the ...
algebra - Select the set of equations that represents the following situation: ...
Algebra - Natalie earns $2.50 for each CD she sells and $3.50 for each DVD she ...
Algebra - Natalie earns $2.50 for each CD she sells and $3.50 for each DVD she ...
math - A vendor at a concert sells new and used CDs. The new CDs cost 2.5 times ...
Algebra - Word Problems (Addition/Elimination Method). Check if my answers are ...
math - How many ways can a person select four books, two CDs, and one DVD from ...

For Further Reading

First Name:
School Subject:
Answer: