Plz ( don’t answer saying a or b. that answer makes 0 ) thx

The general equation for a direct proportion is



where is the constant of proportionality.

If you have just one single (x, y) point of the relation given, you can plug in the values of x and y and solve for k. Once you know k, you write again y = kx, using the actual value of k, and that is the equation of the direct relation.

Naomi's cell phone plan is a direct proportion.
The cost in dollars varies directly with the number of texts.

That allows us to write the general equation of this relation as

y = kx

where is y is cost in dollars, x is the number of texts, and k is the constant of proportionality.

Now we use the given point to find the value of k, the constant of proportionality.

We are told that 16 texts cost $3.20. We have the (x, y) point (16, 3.2).

y = kx

3.2 = k * 16

Divide both sides by 16 to get

k = 3.2/16

k = 0.2

The constant of proportionality is 0.2

Now that we know the constant of proportionality, we just replace k with it, and we have the equation of our relationship.

y = 0.2x

where y = cost of the texts in dollars, and
x = number of texts