Match the systems of equations to their solutions. 2x + y = 12
x = 9 - 2y
x + 2y = 9
2x + 4y = 20
x + 3y = 16
2x - y = 11
y = 11 - 2x
4x – 3y = -13
y = 10 + x
-3x + 3y = 30
2x + y = 11
x - 2y=-7

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a. she will receive a refund of $278.

step-by-step explanation:

5x + 3y = - 4

step-by-step explanation:

the equation of a line in standard form is

ax + by = c ( a is a positive integer and b, c are integers )

express the line first of all in slope- intercept form

y = mx + c ( m is the slope and c the y-intercept )

to calculate m use the gradient formula

m = ( y₂ - y₁ ) / ( x₂ - x₁ )

with (x₁, y₁ ) = (7, - 3) and (x₂, y₂ ) = (4, - 8)

m = = -

y = - x + c ← is the partial equation

to find c substitute either of the 2 points into the partial equation

using (4, - 8 ), then

- 8 = - + c ⇒ c = -

y = - x - ← in slope-intercept form

multiply all terms by 3 to eliminate the fractions

3y = - 5x - 4 ( add 5x to both sides )

5x + 3y = - 4 ← in standard form

the answer is c: divide the arc's degree measure by 360°, then multiply by the circumference of the circle.