Question

Someone help me please, I have been stuck on this question for over an hour and asked this 41 minutes ago. I have to finish this question and 9 others in 1 hour which is when they are due.

The gross income of a business
over time can be represented as
a set of ordered pairs in which
the first element, x, is the
number of the year and the
second element, y, is the gross
income. The gross income is
given for years 1 and 2. A
constant rate of change is
expected for the next several
years.

Year 1 (1997) Gross income
(in 1000's) = $21
Year 2 (1998) Gross income
(in 1000's) = $9


I have done the first two questions it has asked which are below:

The ordered pair that represents
the year and gross income for
1997 is (1,21).

The ordered pair that represents
the year and gross income for
1998 is (2,9).


Here is the question I am stuck on.

The linear equation, y=mx+b,
relating gross income and years
is y=__x+___.

Answer 1

utilizing y = mx + b:

21 = 1m + b
9 = 2m + b

Isolating b in each equation yields:

b = 21 - 1m
b = 9 - 2m

setting b = b yields:
21 - 1m = 9 - 2m

Placing like terms on the same side yields:
2m - 1m = 9 - 21

Solving for m gives:
m = -11

Solving for b gives:
b = 21 -1(-11)
b = 21 + 11
b = 32

Therefore

y = -11x + 32