if 3 drimks cost $9.00, how much will 5 drinks Cost?

Question

if 

3 drinks= $9.00

 

5 drinks=

Answer 1

You can work this as a proportion.

 

x = cost of 5 drinks

 

x/5 = $9.00/3

 

x = (5/3)($9.00) = $15.00

Answer 2

the price per drink is

$9 / 3 drinks = $3 per drink

meaning that 5 drinks cost

5 x $3 = $15

Answer 3

Probably the simplest way to see this is as a proportion:

3/9 = 5/x

You should see directly without much formal calculation that x=15, but if you can't cross multiply and solve.