The image shows a problem asking to find $x$, with an illustration of angles formed by two intersecting lines. There is an expression for each of the angles: $x + 3$ and $2x$, and these angles together form a straight angle, which measures $180^\circ$.

Since the sum of angles on a straight line is $180^\circ$, we can set up the following equation:

$(x + 3) + 2x = 180$

Now, let's solve this equation:

$x + 3 + 2x = 180$ $3x + 3 = 180$ $3x = 180 - 3$ $3x = 177$ $x = \frac{177}{3}$ $x = 59$

Thus, $x = 59^\circ$.

Would you like further details on the solution, or do you have any questions? Here are 5 related questions to consider:

1. What is the definition of a straight angle, and how does it apply to this problem?
2. How would the problem change if the sum of the angles was not $180^\circ$?
3. Can you verify the value of $x$ by substituting it back into the angle expressions?
4. How can you generalize this method to other angle pair relationships?
5. What other types of angle relationships (like complementary or supplementary) exist?

Tip: Always check that the sum of your angles is correct, especially in diagrams involving straight or complementary angles.