Photocopying. Quick Copy recently charged 49¢ per page for color copies and 7¢ per page for black-and-white copies. If Shirlee’s bill for 90 copies was $11.34, how many copies of each type were made?

Question

whpalmer4 · Answer

Let C be number of color copies and B be the number of black and white copies.  Total copies is 90, so B+C=90.  0.49C + 0.07B = 11.34 to tally the costs.  Solve for B and C

texaschic101 · Answer

c = colored copies
b = black and white copies

c + b = 90 -->c = 90 - b
.49c + .07b = 11.34
now just sub 90 - b in for c in the 2nd equation
.49(90 - b) + .07b = 11.34
can you take it from here and solve for b ? And once b is found, sub that back into the 1st equation and solve for c.

whpalmer4 · Answer

I would multiply second equation by 100 to eliminate decimals, and solve first equation to give one variable in terms of the other, then substitute that in second equation.