Answer:
142
Step-by-step explanation:
angle <3 is supplementary to 5x + 3
5x + 3 + 21x - 5 = 180 (because two angles are supplementary as well)
26x - 2 = 180 add 2 to both sides
26x = 182 divide both sides by 26
x = 7
<3 + 5x + 3 = 180 replace x with 7 and rewrite equation
<3 + 38 = 180 subtract 38 from both sides
<3 = 142
