Ch. 2.4
POD
1. A + 27.7 = -36.6
2. M = -4.2
12
Equations with variables on both sides
Solve: 6x + 3 = 8x - 21
First we want to get x on one side….
6x + 3 = 8x – 21
-6x
-6x
Subtract 6x from both sides
and combine like terms
3 = 2x – 21
+21
24 = 2x
2 2
12 = X
+ 21
Add 21 to both sides
Divide both sides by 2
Example 2:
-6d = d + 4
-d
-6d = d + 4
-d
-7d = 4
-7
-7
Practice:
1. Solve: m – 5 = 3m
M = -5/2
2. Solve: 2(c – 6) = 9c +2
C = -2
D = -4/7
You can buy used in-line skates from your friend for $40, or you can
rent some. Either way you must rent safety equipment. How many
hours must you skate for the cost of renting and buying skates to be
the same?
Skates & safety equipment
Cost of
friend’s skates
+
Safety
equipment
rental
=
Skates AND
equipment
rental
**let h stand for the number of hours you must skate
40 + 1.5h = 3.5h
-1.5h
-1.5h
40 = 2h
2
2
h = 20
$3.50 p/h
Safety equipment
$1.50 p/h
ALWAYS DOUBLE
CHECK YOUR ANSWER!!!
A hairdresser is considering ordering a certain shampoo. Company A charges $4 per 8-oz bottle
plus a $10 handling fee per order. Company B charges $3 per 8-oz bottle plus a $25 handling fee
per order. How many bottles must he hairdresser buy to justify using Company B? (how many
bottles do you have to buy in order for both companies to cost the same?)
15 bottles
Practice
#17 from homework:
One telephone company charges $16.95 per month and $.05 per minute for
local calls. Another company charges $22.95 per month and $.02 per minute
for local calls. For what number of minutes of local calls per month is the
cost of the plans the same?
Homework
Pages 98-99 #’s 1-20all