The school store sells 18 folders for $4.50. Select the three unit rates that describe this sale.

$0.25 per folder

4 folders per dollar

36 folders per $9

$3 per dozen

$0.25 per folder - - 1 folder = $0.25

4 folders per dollar - - 1 dollar = 4 folders

$13 per dozen - - 1 dozen =$13

3

step-by-step explanation:

in standard form:

a= dictionaries

b= maps

you have to buy 3 dictionaries, so put a 3 next to the a (dictionaries) so that you can multiply them by each other.

a3+b= 60 (the amount of money you have)

we already know the cost of a=15 so replace a with $15

($15 x 3)+b=60

multiply 15 and 3 to get $45 and replace it with $45

45+b=60

and then replace b with 15 to get the total:

45+15=60

that means you have $15 left after buying 3 dictionaries.

15 divided by the cost of a map ($5) equals 3.

so you can buy 3 maps.

sorry if it was confusing!