math
posted by Anonymous .
A high school has designed the yearbook. A company charges $900 to assembly the master copy and $42 to make additional copies. The total selling price depends on how many copies are made. Write a function rule and determine how much will the school save on ecah book by ordering 600 instead of 200?

in algebic expression method... with those two equation..

Total cost=900+42x
totalcostperbook=totalcost/x= 900/x+42
saveoneachbook=costperbook200costperbook600
= 900/200+42 900/600 42
= 900(1/2001/600)
= 900(400/(200*600))=900 (1/300)= check my work. 
32 less than three fourths of a number