Sue is thinking of buying some 2-liter sodas which are on sale for $1.25 each. The total cost, c, ofall the 2-liter sodas will be proportional to the number of 2-liter sodas, s, that she buys. Which equation represents the relationship between cand s?

first option

a function is a relation in which an input is paired with exactly one output.

so, let's find the right answer.

in our first option, our inputs are january, february, and march. the outputs are 30, 28, and 25. each input has it's own output. this is correct!

our second option we know is incorrect, because ms. valverade has two outputs, dogs and cats. this is not a function.

our third option is incorrect as well. the yellow square has two ouputs, the square and the triangle.

lastly, in our fourth option, we see the number 7 two times with a different output. therefore, this is not a function.

remember: each input must be paired with only one output!

answer is  

a.

5.56

hope you get this right.