He is wrong because as long as they have the same terms/ variables behind the number it doesn’t matter about if it is positive or negative
Answer:1/2 y
Step-by-step explanation:
We can solve this using ration reasoning:
x
2
x
1
=
y
2
y
1
Explanation:
If
x
varies directly with
y
(written
x
∝
y
), then doubling
y
means doubling
x
, so the rations of final values and initial values will be the same:
x
2
x
1
=
y
2
y
1
In this case,
x
2
9
=
24
18
x
2
=
9
⋅
24
18
=
12
Or, intuitively, if
x
∝
y
and
x
=
9
when
y
=
18
, we can conclude that
x
=
1
2
y
and
1
2
of 24 is 12.
He made a mistake at step 3. He should subtract 15 from both side instead of adding 15 to both side.
Answer: C