hmm
rate=change in price/change in number of books
see left one
notebooks,money
6,1.8
12,3.6
change in money/change iin notebooks=(3.6-1.8)/(12-6)=1.8/6=0.3
rate is 0.3 for left one
rate is 30 cetns per notebook
right one
number of books,price
3,1.05
6,2.1
change in money/change in notebooks=(2.1-1.05)/(6-3)=1.05/3=0.35
price is 35 cents per
12*35=420 cents=$4.20
the blank on bottom right is $4.20
the rate on the left is $0.30 per notebook
the rate on the right is $0.35 per notebooks
left one is the better deal