how to find x?

Question

1/3x+5=9

1/8a-6=1

x/4+7=-2

9-4m=19

X/7-8=-10

Answer 1

Hi Victorya,

 

When solving for 'x' or any variable your instructor may use to represent an unknown number, the trick lies in getting that variable alone on one side of the equal sign. Your math teacher probably referred to this as 'isolating the variable' You can achieve this by using the opposite function to move the known numbers to one side of the equal side. 

 

For example in your first equation,

 

1/3x + 5 = 9

 

First subtract 5 from both sides, 

 

1/3x + 5 = 9

         -5    -5

 

1/3x=4

 

Next, to get rid of the 1/3, you would multiple both sides by 3 

 

1/3x(3) = 4(3)

 

so you have x=12.

 

You can check your work by plugging in 12 for x and see if we are right 1/3(12) + 5 = 9

 

I hope this helps...all of your problems follow the same pattern, so hopefully you can use this to solve the rest:)

 

Thanks, 

Aundriel P., ATL