Ch. 2.4

1.

A + 27.7 = -36.6

2.

M = -4.2

12

POD

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 3 = 2x – 21 +21 + 21 24 = 2x 2 2 Subtract 6x from both sides and combine like terms Add 21 to both sides Divide both sides by 2 12 = X

Example 2:

-6d = d + 4 -d -d -6d = d + 4 -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 $3.50 p/h

Safety equipment

$1.50 p/h 40 + 1.5h = 3.5h

-1.5h -1.5h

40 = 2h 2 2 h = 20

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?

Pages 98-99 #’s 1-20all

Homework