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Studying for a test? Prepare with these 3 lessons on Simple equations.

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# One-step equations intuition example

Video transcript

Now you've got your
chance to use this scale to figure out how
much something weighs. So we're asked, how much
does Old Spice Man weigh? We have Old Spice Man,
this little guy here, plus you have 3 blocks. So on the left-hand
side, you have Old Spice Man plus 3 blocks. And you see that the
scale is balanced. On the right hand side,
you have 8 blocks. So Old Spice Man plus
3 is equal to 8 blocks. And you can see what
happens when we do something to one side of the
scale or another. If we were to take a block
from the right-hand side, all of a sudden, the right-hand
side becomes lighter and it tilts up. And our scale is
no longer balanced, and we can no longer
say that the left and the right-hand
side is equal. And there's an explanation
of it below here. So what we want to do
is add or remove blocks from the left or
right-hand sides. So essentially we're
just left with Old Spice Man on the left-hand side,
but the scale is balanced. So whatever is on
the right-hand side is how much he weighs in blocks. So let's see if we can do that. So let me add that block back. That's where we started from. So let's see, I want
to get rid of these 3. So if I take 1 away
from the left-hand side, well, I can't just do it there,
because now, all of a sudden, the left-hand side is too light. So I'm going to have to take 1
away from the right-hand side as well. Well, let me do it again. Take 1 away from
the left-hand side. We'll have to do 1 from the
right-hand side as well. And I'm getting close-- 1
from the left-hand side, now 1 from the right-hand side. And it is a balanced. Old Spice Man is
equal to 5 blocks. And you see what happened
here algebraically. I took 1 from the left
and right-hand side. I did it 3 times. So we started with
essentially Old Spice Man, or you could call it x, plus 3. But then we ended up subtracting
3 from the left-hand side and subtracting 3 from
the right-hand side. So we subtracted the same
number from both sides to get the weight
of Old Spice Man. And we could check
it right over here. And very good.