Question

1. a 3-ounce can of tomato sauce costs $1.68. in cents, what is the price per ounce ?

2. how many cds can edward buy for $14 each and spend the same amount he would to buy 60 cds for $7 each ?

Answer 1

1) 5.6 cents

2) 30 cds

Explanation:

For both problems we can use the Rule of Three:

1) If 3 ounces of tomato sauce cost
`\$1.68`, how many will cost 1 ounce?:

3 oz ---
`\$1.68`

1 oz --- ?

Then:

`?=((1 oz)(\$1.68))/(3 oz)`

`?=\$ 0.056`

This is the price in dollars, now we have to calculate it in cents, taking into account that
`100 cent=\$1`:

`$ 0.056 (100 cent)/(\$1)=5.6 cents` This is the price in cents of 1 ounce of tomato sauce

2) If Edward buys 60 cds for
`\$ 7` each, what is the cost of 60 cds?:

60 cds ---?

1 cd ---
`\$7`

`?=((60 cds)(\$7))/(1 cd)`

`?=\$ 420` This is what Edward spends in 60 cds for
`\$7` each

Now, we have to calculate how many cds Edward can buy for
`\$14` each and spend the same
`\$ 420`:

1 cd ---
`\$14`

? cds ---
`\$ 420`

`?=frac{(\$ 420)(1 cd)}{\$14}`

Finally:

`?=30 cds`