The equation that models the balance y after x is y = -145x + 1400
<h3>How to find the equation?</h3>given that
Zachary uses a payment plan to buy a PC for $1,400. His balance was $820 four months after he made the computer purchase. His amount was $240 eight months after he made the computer purchase.
Assume it has to do with developing an equation that represents this loan as a function of time. Use the loan amount as Y and the time as X.
Now Put that in the standard format:
Y = mX + b
according to the question
at x = 0 then y = 1400
at x = 4 then y = 820
at x = 8 then y = 240
now find the slope
points are (4,820) & (8,240)
slope = -145
now the equation is y = -145x + b
Let x = 4 & y = 820
then
820 = -145(4) + b
820 = 580 + b
b = 820 + 580
b = 1400
finally the equation is
y = -145x + 1400
Learn more about algebraic equations from here::
#SPJ9