(a)
Since SW is tangent to the circle, the angle formed between the tangent and the diameter is 90°:
m∠WSR = 90°
(b)
Arc RT has a measure of 24°. The inscribed angle is half the measure of the corresponding arc, thus:
m∠RST = 1/2 x 24° = 12°
m∠RST = 12°
(c)
Angle WST is the sum of angle WSR and RST:
m∠WST = m∠WSR + m∠RST
m∠WST = 90° + 12°
m∠WST = 102°