Answer:
-2x = -60
Isolate x and simplify.
2x = 60
x = 30
Straight vertical line through x=30.
Answer:

Step-by-step explanation:
tan(30°) = 
cot(30°) = 
sin(60°) = 

Since complementary angles add to 90°, (4x - 1) and (5x + 19), also add to 90°.
Thus, lets form an equation:
90 = 5x + 19 + 4x - 1
72 = 9x
x = 9
Thus, the measure of angle B is 64°.
Join the centre O to the chord (let it be MN) & let OH be the perpendicular to the chord
OH bisects MN into 2 equal parts (each one is x/2)
OMH is a right triangle with one side =8, the second leg =x/2 & the hypotenuse = 12 (Radius)
Apply Pythagoras:
12² = 8² +(x/2)² ==>144=64 + x²/4 ==> x²=4(144-64) =320
x²=320==> x=√320 =17.88 ≈17.9
17,98 $ (subtraction)
Hope that helpful !