## anonymous one year ago solve bx-cx=7 for x

1. SolomonZelman

Do you know anything like the folowing rule? $$\large\color{black}{ \displaystyle ab+zb=(a+z)b }$$

2. SolomonZelman

Don't be afraid to say no....

3. anonymous

I really dont know

4. SolomonZelman

it is fine.

5. SolomonZelman

Ok, would you agree with me if I said that: $$7x-4x=3x$$ ?

6. anonymous

no hold on

7. anonymous

Here is the full question, with options

8. SolomonZelman

I don't really need that to do it..... I am just trying to get you to understand how to work ouy the solution:) So, back to what I asked, if you will. In general: $$7x-4x=3x$$ Do you agree with me or not?

9. anonymous

I do

10. SolomonZelman

Ok, and same way: $$10x-2x=8x$$ $$9x-3x=6x$$ and so forth.

11. SolomonZelman

Now, when you do $$bx-cx$$ you are going to have a "b-c" number of x's. Right?

12. anonymous

Yes

13. SolomonZelman

So, you can re-write this: $$bx-cx=7$$ as: $$(b-c)\times x =7$$

14. SolomonZelman

good with the step that I did just now, or you have questions about it?

15. anonymous

Good with the steps

16. SolomonZelman

Ok, so we have so far: $$(b-c)\times x=7$$ ---------------------- If I had $$4x=8$$, and I wanted to solve for x, THEN, I would divide both sides by 4. $$4x\div4=8\div 4{~~~~~}\Rightarrow{~~~~~} x=2$$

17. SolomonZelman

So, what whould I do when instead of 4 (as I showed in the example), I have a $$"b-c"$$ (as we have in our problem now).

18. anonymous

Alright I sorta got it

19. SolomonZelman

Ok, s when we have: $$(b-c)\times x=7$$ we are going to divide both sides by: $$(b-c)$$

20. SolomonZelman

Can you preform this division for me please?

21. SolomonZelman

perform*

22. anonymous

x/(b-c) ?

23. SolomonZelman

x=7/(b-c)

24. anonymous

Thank You :)