Question

Carrie uses her phone primarily to take a lot of selfies. The storage space on her phone is limited, so Carrie needs to keep track of how many selfies she takes.

There is a proportional relationship between the number of selfies Carrie takes, x, and the amount of storage (in megabytes) she uses taking selfies, y.
x (selfies) y (megabytes)
10 20
12 24
21 42
22 44
Write an equation for the relationship between x and y. Simplify any fractions.
y=

Answer 1

Answer: y = 2x

Step-by-step explanation:

A direct proportion is of the form y = kx

To find k, pick any row to divide the y over x value

• k = y/x = 20/10 = 2
• k = y/x = 24/12 = 2
• k = y/x = 42/21 = 2
• k = y/x = 44/22 = 2

No matter which row you go for, the constant of proportionality is 2. Meaning that we double the x value to get to y.

Therefore, we go from y = kx to y = 2x