Question

If 10 glasses cost 40 dollars, how much do 18 glasses cost?

Answer 1

$72

Explanation:

Let's set up a proportion using the following setup:

`(cost)/(glasses) =(cost)/(glasses)`

We know that it costs $40 for 10 glasses.

`(40)/(10 ) =(cost)/(glasses)`

We don't know the cost for 18 glasses. Therefore, we can say it costs
`x` for 18 glasses.

`(40)/(10) =(x)/(18)`

We are trying to solve for
`x`, the cost of 18 glasses. Therefore, we must isolate it.

`x` is being divided by 18. The inverse of division is multiplication. Multiply both sides of the equation by 18.

`18*(40)/(10) =(x)/(18)*18`

`18*(40)/(10) =x`

`18*4=x`

`72=x`

x= $72

18 glasses cost $72.00

Answer 2

40 divided by 10 = 4, this is the cost for one.
4 multiplied by 18 = 72, this is the cost for 18