To find the measure of the second angle, start by recognizing that adjacent angles on a straight line add up to 180°.
Given:
- First angle = \( (5x - 28)° \)
- Second angle = \( (8x)° \)
According to the straight angle theorem: \[ (5x - 28) + (8x) = 180 \]
Combine like terms: \[ 13x - 28 = 180 \]
Now, add 28 to both sides: \[ 13x = 208 \]
Next, divide by 13: \[ x = 16 \]
Now substitute \( x \) back into the expression for the second angle: \[ 8x = 8(16) = 128° \]
Therefore, the measure of the second angle is: \[ \boxed{128°} \]