Sarah went to an electronics store, purchased 3 CDs and 5 DVDs, and spent $137. Michelle went to the same store.bought 2 CDs and 7 DVDs and spent $161. How Much does each CD sell for at the store?

Question

anonymous · Answer

let C = cd and D = dvd.  3c + 5d = 137. Solve for one variable and plug into the other equation,  2c + 7 d = 161.

anonymous · Answer

let the cost of CD's be x and DVD's be y
3x+5y=137-------eq1
2x+7y=161-------eq2
now multiply 1st equation with 2nd and second equation with 3 
6x+10y=274------1
6x+21y=483------2
now subtract equation 2 from 1
and u will get,
-11y=-209
y=19
now substitute y in one of the equations
3x+5(19) = 137
3x = 137-95
x = 42/3
x = 14
so,the cost of a CD is 14 and DVD is 19