Aprinter that costs $60 requires replacement cartridges that sell for $23. over the life of the printer the cost of the printer and replacement cartridges is $865. how many cartridges were used over the life of the printer?

In order to solve this you are going to need to make an equation to solve it. One way is that we can make the amount of replacement cartridges into the variable of x. You need to equal all of it to 865 by doing this:

865 = 60 + 23x

Subtract each side by 60 to isolate the 23x.

805 = 23x 

Divide each side 23 

x = 35

35 cartridges have been used over the life of the printer

What do you mean by that?