Video Transcript
William is playing a board
game. From start, he moves 10 spaces
forward. In his next turn, he moves six
spaces back. How many spaces away from start is
he now?
If William begins on start and he
moves 10 spaces forward. On his next turn, he moves six
spaces back. We want to know how many spaces is
he away from start. For this unknown value, we can use
the variable 𝑥. What kind of equation can we write
to model the situation? We can write it a few different
ways. First, William went forward 10
spaces. So, we can start with positive
10. And then, he went back six
spaces. We can represent that
mathematically with negative six. If you take positive 10 and
subtract six, you’ll get 𝑥, the number of spaces away he is from the start. 10 minus six equals four. And that means our 𝑥-value is
four.
Currently, the way it’s written: it
says four equals 𝑥. But it’s fine to rearrange it in a
more common way: 𝑥 equals four. 10 minus six equals 𝑥 is only one
way to model this situation with an equation. We could say that 𝑥 — the number
of spaces away from start William is — plus the six places backwards he walked must
be equal to the 10 total forward spaces. If 𝑥 plus six equals 10, then we
can solve the problem by subtracting six from both sides of the equation. 𝑥 plus six minus six equals 𝑥
plus zero, which is 𝑥, and 10 minus six equals four. Both methods show us that William
is four places away from start.
