## anonymous one year ago What is the value of x in the proportion. x/2=16x-3/20 1. 2 2. -3/2 3. 1/4 4. 1/2

1. whpalmer4

$\frac{x}{2} = \frac{16x-3}{20}$ is that how the problem reads?

2. anonymous

yes

3. whpalmer4

4. anonymous

yes

5. whpalmer4

Good. Cross-multiply and solve the resulting equation for $$x$$

6. anonymous

actually i am confused on how to cross multiply on this can you explain?

7. whpalmer4

Okay, $\frac{x}{2} = \frac{16x-3}{20}$ multiply the numerator of one by the denominator of the other $x*20 = 2*(16x-3)$$20x = 32x - 6$

8. whpalmer4

What you are effectively doing is making a common denominator of 1

9. whpalmer4

Can you solve $20x = 32x - 6$ for $$x$$?

10. anonymous

x=1/2

11. whpalmer4

let's try it in the original equation and make sure it works: $\frac{\frac{1}{2}}{2} = \frac{16(\frac{1}{2})-3}{20}$$\frac{1}{4} = \frac{8-3}{20}$$\frac{1}{4} = \frac{5}{20} = \frac{1}{4}\checkmark$

12. anonymous

Okay i get it now thanks!

13. anonymous

Can you help me with one more?

14. whpalmer4

We could also solve like this: $\frac{x}{2} = \frac{16x-3}{20}$Multiply both sides by 20$20*\frac{x}{2} = 20*\frac{16x-3}{20}$$10x = 16x-3$$10x-10x+3 = 16x-10x+3-3$$3=6x$$x=\frac{1}{2}$

15. anonymous

Wait so 1/2 is the answer or 1/4?

16. whpalmer4

the answer is x = 1/2. what I did was plug the value we got for x back into the original equation to make sure that it made a true statement. Let's say that I made a mistake somewhere and decided that $$x=2$$ is the right answer. Well, when I plug that back into the original, I get: $\frac{2}{2} = \frac{16(2)-3}{20}$$1 = \frac{29}{20}$and that is not true, so that means that $$x=2$$ is NOT the correct answer.

17. anonymous

Ohhh okay thank you so much. I am gonna open another question can you help me?

18. whpalmer4

sure, just "tag" me by putting "@whpalmer4" in a response and I'll get a notification