Ok. I ll try to clarify. Considering what I know and not being arrogant as someone said before. Ten years I help students here, on this amazing website/forum for free, and people label me arrogant. Mah
Is 0 a Multiple of $10 ?$
- Yes, 0 is a multiple of every integer, including 10.
- Mathematically, a number $k$ is a multiple of $n$ if $\(k=n \times m\)$ for some integer $m$.
- Since $\(0=10 \times 0,0\)$ is a multiple of 10 .
Re-evaluating the Problem with This in Mind
Given:
- Angles on a straight line: $\(60^{\circ}, x, 2 y\)$ (sum $\(=180^{\circ}\)$ ).
- All angles are multiples of 10.
- $\(x>90^{\circ}\)$.
From earlier:
$$
\(x=120-2 y\)
$$
Constraints:
1. $\(x>90^{\circ} \rightarrow y<15^{\circ}\)$.
2. $x$ and $2 y$ must be multiples of $\(10 \rightarrow y\)$ must be a multiple of 5 (since $\(2 y\)$ must be divisible by 10 ).
Testing Option A: $y=0$
- $\(2 y=0\)$ (valid multiple of 10 ).
- $\(x=120-0=120^{\circ}\)$ (valid, since $\(120>90^{\circ}\)$ and is a multiple of 10 ).
- Angles: $\(60^{\circ}, 120^{\circ}, 0^{\circ} \rightarrow\)$ Sum $\(=180^{\circ}\)$.
Conclusion:
- $\(y=0\)$ is mathematically valid because:
- It satisfies $\(y<15^{\circ}\)$.
- $\(2 y=0\)$ is a multiple of 10 .
$\(\circ x=120^{\circ}\)$ is a multiple of 10 and $\(>90^{\circ}\)$.
Should We Exclude $y=0$ ?
- Geometrically, an angle of $\(0^{\circ}\)$ means the two rays coincide (no opening).
- Some problems may implicitly assume angles are positive, but the problem statement does not explicitly exclude $\(0^{\circ}\)$.
- Since $\(\mathbf{0}\)$ is a multiple of $\(\mathbf{1 0}\)$, and no restrictions are given, Option $\(\mathbf{A}(\mathbf{0})\)$ must be considered valid.
Final Valid Options
From the given choices:
- A (0) - Valid (mathematically and logically, unless excluded).
- C (5) - Valid ( $\(y=5, x=110^{\circ}, 2 y=10^{\circ}\)$ ).
- D (10) - Valid ( $\(y=10, x=100^{\circ}, 2 y=20^{\circ}\)$ ).
B (2) and E (20) are invalid (as previously determined).
Final Answer
If $\(0^{\circ}\)$ is allowed, the correct options are:
\(A, C, D\)
However, if the problem assumes angles must be positive, then only:
\(C, D\)
Since the problem does not explicitly exclude $0^{\circ}$, the most complete answer is:
$\(A, C, D\)$
But if the context implies only positive angles, then:
$\(C, D\)$
(
Most standardized tests would likely expect $\(\boldsymbol{C}\)$
and $\(\boldsymbol{D}\)$
only, but strictly speaking, $\(\boldsymbol{A}\)$
is also correct unless specified otherwise.)