1/3x = 1/2x - 5

5 = 1/6x

x = 30

Is this right? If it is, how can I check it to show that it's right? Please help. Thnx so much!

Results 1 to 4 of 4

- May 3rd 2007, 05:54 AM #1

- May 3rd 2007, 06:01 AM #2
is it 1/2x - 5 or 1/(2x - 5)?

you can check by pluging in your answer into the original equation and see if everything checks out. you got x = 30, so

1/3(30) should be equal to 1/2(30) - 5

not true, your answer would be wrong either way, whether it is 1/2x - 5 or 1/(2x - 5)

- May 3rd 2007, 06:10 AM #3
Hmm...well the problem is:

One-third of a number is 5 less than half of the same number. What is the number?

and I had posted this before and someone gave me the answer of:

1/3x = 1/2x - 5

5 = 1/6x

x = 30

but when I went to check it I couldn't get it to make sence. I'm stuck. Can you please help me?! Thanks in advance!

- May 3rd 2007, 05:46 PM #4
well, you set up the equation correctly, so good job there

now to solve this thing

(1/3)x = (1/2)x - 5 ..........we want x on one side

=> (1/3)x - (1/2)x = -5 ....subtracted (1/2)x from both sides

=> (1/3 - 1/2)x = -5

=> (-1/6)x = -5

=> x = 30 ......................multiplied both sides by -6

Ah, so you were correct!!! I misinterpreted what you wrote due to your lack of parenthesis. i thought you meant to write either 1/2x - 5 or 1/(2x - 5) not (1/2)x - 5 ...........do you see the difference between the three?

You were not confident in your answer, why? we can check it. plug in x = 30 in both sides and see if they end up the same:

(1/3)(30) = 10 .......................this is what the left side gives

(1/2)(30) - 5 = 15 - 5 = 10 ......this is what the right side gives

so you see, they are equal, you did good