Posted by Rick on Thursday, September 30, 2010 at 6:31pm.
One day a store sold 45 pens, the zippedy do's at $8.50 & The Royal Blues at $9.75. In all, $398.75 was spent on the pens. How many Royal Blues were sold that day?

algebra  bobpursley, Thursday, September 30, 2010 at 6:32pm
45=Z+R
9.75R+8.5Z=398.75
R=45Z
put that in for R in the second equation, and solve.