Ryan starts saving money to buy a car right after his 16th birthday. he already has $120 from his birthday. after 3 months he has $840 altogether. after 10 months he has $2520 altogether. find the linear equation that models the data. using your equation, find how much money ryan will have altogether after saving for 2 years?

Remark

The basic equation is y = mx + b

y = the total amount of money

m = The amount of money he save each month (it is a constant).

b = the y intercept which is his starting amount or 120 dollars.

x = the number of months (this is a variable).

After 3 months he has 840 dollars. That's y

840 = 3*m + 120    Subtract 120  from both sides

840 - 120 = 3m

720 = 3m

240 = m   So he saves 240 every month.

Now the equation becomes.

y = 240 * x + 120

Savings after 24 months

y = Total

m = 240 dollars/month

x = 24 months

b = 120

y = 24*240 + 120

y = 5760 + 120

y = 5580

He had 5580 dollars after saving for 2 years (or 24 months total) This assumes that when he started, he took his birthday money and added a 1 month payment to it

really really sorry if i'm

-12 -5(x + 4) = 3x

-12 - 5x - 20 = 3x

-12 - 20 - 5x = 3x

-32 - 5x = 3x

    + 5x   + 5x

-32 = 8x

8         8

- 4= x

this is the formula: v = the value of investment at the end of the time period

p = the principal amount (the initial amount invested)

r = the annual interest rate

n = the annual frequency of compounding (how many times a year interest is added)

t = the number of years the money is invested

^ means raise to the power of