# i need help with this problem

1/3x < 21 :?

#### emmaiskool242

##### Junior Member
i'm not sure how to do this one, what is the section called in your book, then i might be able to help you more. Because I think I know how to do it but i'm not quite sure

G

#### Guest

##### Guest
janetfizz said:
1/3x < 21 :?

1/3x < 21

Multiply both sides by three to get rid of the fraction.

x < 63.

Sorry, I made a really stupid mistake. I wasn't thinking.

#### pka

##### Elite Member
You have not given a very clear statement of your problem!
Depending of which it means:
$$\displaystyle \begin{array}{l} \frac{1}{{3x}} < 21\quad \Rightarrow \quad \frac{1}{{63}} < x \\ \frac{1}{3}x < 21\quad \Rightarrow \quad x < 63 \\ \end{array}$$

EDIT: Aly, before you answer please be sure you know what you are doing!

G

#### Guest

##### Guest
Re: thanks

janetfizz said:
thank you very much how do you do 5p-7=18 and y-14.4< 18.39
Well, I don't want to do your homework for you, but the help I can give you is so straightforward that it'll give you the answer. I'll help you with the second one, and then I'll give you a hit about the first one.

y-14.4 < 18.39

y < 22.79

For the first one, try adding the seven. Then finish out the problem. See what you get. Always make sure you have your numbers on one side and your variable on the other when working problems like these out.

G

#### Guest

##### Guest
pka said:
You have not given a very clear statement of your problem!
Depending of which it means:
$$\displaystyle \begin{array}{l} \frac{1}{{3x}} < 21\quad \Rightarrow \quad \frac{1}{{63}} < x \\ \frac{1}{3}x < 21\quad \Rightarrow \quad x < 63 \\ \end{array}$$