1. **State the problem:** Given two parallel lines $m \parallel n$ cut by a transversal, find the values of $x$ and $y$ given the angles $(2x + 10)^\circ$ on line $m$, and $(8x - 20)^\circ$ and $y^\circ$ on line $n$.
2. **Identify angle relationships:** Since $m \parallel n$, corresponding angles are equal, and alternate interior angles are equal. The angle $(2x + 10)^\circ$ on line $m$ corresponds to the angle $(8x - 20)^\circ$ on line $n$ because they are alternate interior angles.
3. **Set up the equation for $x$ using alternate interior angles:**
$$
2x + 10 = 8x - 20
$$
4. **Solve for $x$:**
$$
2x + 10 = 8x - 20
\\
10 + \cancel{2x} = 8x - 20 - \cancel{2x}
\\
10 = 6x - 20
\\
10 + 20 = 6x
\\
30 = 6x
\\
x = \frac{30}{6} = 5
$$
5. **Find $y$:** The angle $y^\circ$ is adjacent to $(8x - 20)^\circ$ on line $n$ and together they form a straight line, so they are supplementary angles.
6. **Write the supplementary angle equation:**
$$
(8x - 20) + y = 180
$$
7. **Substitute $x=5$ into the equation:**
$$
8(5) - 20 + y = 180
\\
40 - 20 + y = 180
\\
20 + y = 180
$$
8. **Solve for $y$:**
$$
y = 180 - 20 = 160
$$
**Final answers:**
$$
x = 5, \quad y = 160$$
Parallel Lines 015C73
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