If we say A = ream of paper and B = cost of ink than we can set-up an expression to calculate when A is equal to a number what the number of B will be.
Maximim of 270$ so anything we buy must be equal to this.
Ream of paper cost 6$ each so 6A represents the number of reams bought since we said A is number of reams of paper.
Ink Cartridges are 18$ each so 18B would represent this based on B = to cost of ink.
Now setting up our equation
6A + 18B = 270
When A = 1
B = 14.67 Ink Cartridges
When A = 1 Ream ofpaper