Bill F. answered • 11/29/13

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Hi Kath. To solve equations, the number one thing to remember is: What you do to one side of an equal sign you must do to the other side.

a)

2x + 1 = 7

your goal here is to get x all by itself on the left side. So, first subtract 1 to BOTH sides

2x + 1 = 7

- 1 -1

2x = 6

Now, to get rid of the 2 in front of the x (by the way, 2x means 2 times x), you must divide BOTH sides by 2.

2x = 6

2 2

Thus, you have your answer:

x = 3

b)

2x - 9 = 25 (add 9 to BOTH sides)

+9 +9

2x = 34 (divide BOTH sides by 2)

x = 17

c)

5 x - 20 = 3x - 8 (first get x on the left side by subtracting 3x from BOTH sides)

-3x -3x

2x - 20 = -8 (add 20 to BOTH sides)

+20 +20

2x = 12 (divide BOTH sides by 2)

x = 6

d)

I think the problem is this:

4r - r = 15

4

Multiply all THREE terms by 4 to get rid of the fraction

16r - r = 60 (16r - r is 15r.......just think of r as 1r)

15r = 60 (divide BOTH sides by 15

r = 4