SOLUTION: David has been working for his company since 1990. Each year he gets a $2100 raise, in 1998 he earned one and a half times as much as he earned in 1990. Write an equation in the f

Question 693720: David has been working for his company since 1990. Each year he gets a $2100 raise, in 1998 he earned one and a half times as much as he earned in 1990.
Write an equation in the form of y=mx+b that models David's salary y in terms of number of years x since he started working there. What was his salary in 1998? How much will he earn in 2005?
Found 2 solutions by stanbon, josmiceli:
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
David has been working for his company since 1990. Each year he gets a $2100 raise, in 1998 he earned one and a half times as much as he earned in 1990.
Write an equation in the form of y=mx+b that models David's salary y in terms of number of years x since he started working there. What was his salary in 1998? How much will he earn in 2005?
--------
Let his salary in 1990 be "y" ; Then his slary in 1998 is (3/2)y.
Form: y = mx + b
m = 2100 because slope is the change in y when x increases by 1.
---
Using (0,y)
y = 2100x + b
y = b (the 1st years salary)
----
Using (8,(3/2)b)
(3/2)b = 2100(8) + b
(1/2)b = 2100*8
b = 2100*16
$33,600 (1st year salary)
--------
Equation:
y = 2100x + 33,600
----
Salary in 1998:
f(8) = 2100*8 + 33,600 = $50,400
-----
Salary in 2005
f(5) = 2100*5 + 33,600 = $44,100
=================================
Cheers,
Stan H.
====================

Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
I can call 1990, the year he started work,
1991 will be
The slope will be ( change in y ) / ( change in x ), so
( the 1 stands for 1 year )

given:

-----------------
So far I have

Now I can say

and also

--------------
Now I have the final equation

---------------------
His salary in 1998 was

$50,400
-----------
In 2005 he will earn

$65,100
-----------
Check:
Is the slope between and
equal to ?

OK
---------
Here's a plot:

RELATED QUESTIONS
Please help and show all steps. Thanks A man gets a job with a salary of 39200 dollars (answered by stanbon)
Nick was stunned when he opened the mail. Here was a check for $332.50! This was the... (answered by richwmiller)
Jhon started a job that paid $20,000 a year. Each year after the first, he received a... (answered by ewatrrr)
Juan earns $14.80 an hour. He gets a 10% raise each year. What will his rate of pay be... (answered by addingup)
For his phone service David pays a monthly fee of $11 , and he pays an additional (answered by ewatrrr,josmiceli)
sam has been working since he is 15. 1/4 of his life as a baseball player, 1/5 as a... (answered by josgarithmetic)
Nathan, who has been working for a consulting firm, is thinking of starting his own... (answered by solver91311)
In 1999, boys' soccer had 142 members and has increased 12 students per year since 1990.... (answered by josmiceli)
Interest. A high school student was able to save $8000 by working a part-time job every... (answered by stanbon)