2. here is a linear equation in two variables: 2x + 4y - 31 = 123.
solve for x: 2x + 4y - 31
123
solve for y: 2x + 4y - 31 = 123

Part 1)

Part 2)

Step-by-step explanation:

we have

Part 1) Solve for x

That means -----> isolate the variable x

Subtract 4y both sides

Adds 31 both sides

Divide by 2 both sides

Part 2) Solve for y

That means -----> isolate the variable y

Subtract 2x both sides

Adds 31 both sides

Divide by 4 both sides

this is a direct variation proportion. y = kx

y is the total amount due, k is the constant of variation, and x is the number of texts sent.

plug in the 3.20 and the 16 to solve for the "k". this is the constant of proportionality. it is the value that will not change.

3.20 = k(16). solving you get $.20 per text.

the equation would then be y = .20x