Answer:
y = 12665 (100⁻¹) + b
Step-by-step explanation:
To model this relationship, you're to write the equation of a line; in the form
y = mx + b
Now let y represent the full coupon value,
mx represent the amount spent by Hellen and her sister
and b, the change that's left on the coupon.
So, the summary of Hellen's transaction is:
$85.2 became $(85.2 - 12.78) which is = $72.42
The summary of her sister's transaction is:
$63.8 became $(63.8 - 9.57) which is = $54.23
So y - (72.42 + 54.23) = b
y - 126.65 = b
y = 126.65 + b
Separating m from x in mx, you have
y = 12665 x 1/100 + b
y = 12665 (100⁻¹) + b
Where m = 12,665 and x = 100⁻¹
