Question

How do you solve `7- 3( 5t - 10) = 67`?

Answer 1

Distribute the `-3` first.

Explanation:

You may be tempted to subtract `7` and `3` but that is the wrong thing to do. Subtracting `3` is the same thing as a negative `3`, so we should distribute the `-3` to everything in the parenthesis.

Distributing the `-3`:

• Multiply `-3` by `5t` to get `-15t` and multiply `-3` by `-10` to get positive `30`

`7-15t +30=67`

The `7` and the `30` both have no variable, so these can be combined.

`7+30=37`

Now we're left with

`37-15t=67`

The next step would be to subtract `37` from both sides. Remember, the goal with these kinds of equations is to isolate the variable to get our answer. `37-37` cancels out, and `67-37` is `30`.

We're left with

`-15t= 30`

When a variable term is equal to a constant term, you always divide by the coefficient of the variable (number in front of variable).

The coefficient is `-15`. Dividing `-15t` by `-15` will just leave `t`, and `30/(-15)` is equal to `-2`. This means

`t= -2`

I'm in the 9th grade and I did a problem like this today :)