For the case of a line through
(
2
,
7
)
and
(
1
,
−
4
)
we have
slope
m
=
Δ
y
Δ
x
=
−
4
−
7
1
−
2
=
−
11
−
1
=
11
Using the point
(
2
,
7
)
we can write the equation of the line in point slope form as:
y
−
7
=
m
(
x
−
2
)
where the slope
m
=
11
.
That is:
y
−
7
=
11
(
x
−
2
)
To get point intercept form, first expand the right hand side so...
y
−
7
=
11
x
−
(
11
⋅
2
)
=
11
x
−
22
Then add
7
to both sides to get:
y
=
11
x
−
15
=
11
x
+
(
−
15
)
This is point intercept (
y
=
m
x
+
c
) form with slope
m
=
11
and intercept
c
=
−
15
.
<span>22% of $40 is $8.80 so the now rate should be $40.00+$8.80=$48.80</span>
