Question

Um help! how do I do this?

Answer 1

1/2 t-4(2+t)=20
1/2 t-8-4t=20
least common multiple=2
t-16-8t=40
-7t=40+16
-7t=56
t=56/-7=-8

Answer: t=-8

To check
-8/2 - 4(2-8)=-4-4(-6)=-4+24=20

Answer 2

You do it just exactly as the question says:  Take one choice,
substitute it in place of 't' in the given equation, and see if the
equation becomes a true statement.

I'll do 'A' for you:

Does 't' = 8 ? 
Let's see.
If it does, then             (1/2) (8)  -  4(2 + 8)  =  20

                                     (     4    )  -  4(  10  )  =  20

                                     (     4    )  -      40       =  20

                                                  -36               =  20 .

Is that a true statement ?     Is  -36 = 20  ?
I don't think so.
=>  't' is not 8 .     
      'A' is not the correct choice.

Now go ahead and try 'B'.
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It might be faster and easier to just take the equation and solve it.
Then you'll know what 't' is, and you won't have to try any suggestions.

Here's the equation:              (1/2) (t) - 4(2 + t)  =  20

Eliminate parentheses
on the left side:                        1/2 t    - 8 - 4t  =  20

Combine the 't's
on the left side:                        -3.5 t  -  8        =  20

Add  8  to each side:               -3.5 t               =  28

Multiply each side by  -1 :         3.5 t               = -28

Divide each side by  3.5 :               t               = - 8 .

Now you can look back at the choices
and see that 'B' is the one you want.