8. OA, OB and OC are three straight lines. (i) Work out the size of the angle marked x. (ii) Give a reason for your answer.

## Step 1: Understanding the problem<br />The problem is about finding the size of an angle marked \( x \) in a figure with three straight lines \( OA, OB, \) and \( OC \). The figure is not provided, but we can assume that the lines intersect at point \( O \) forming angles between them. <br /><br />## Step 2: Identifying the type of angles<br />In the absence of the figure, we can't identify the exact type of angles. But, in general, the angles formed by intersecting lines can be vertical angles, adjacent angles, or supplementary angles. <br /><br />## Step 3: Calculating the angle<br />The size of the angle \( x \) can be calculated based on the given information about the other angles. If we know the size of the other angles, we can use the properties of the angles to find \( x \). For example, if \( x \) is a vertical angle to another angle, then they are equal. If \( x \) is adjacent to another angle, then they add up to the angle formed by the intersecting lines. If \( x \) is supplementary to another angle, then they add up to \( 180° \).<br /><br />### Important formula: <br />The sum of the angles on a straight line is \( 180° \).