1. **State the problem:** We have three rays meeting at a vertex forming three angles: 94°, angle $b$, and a reflex angle of 243°. 2. **Understand the angles around a point:** The sum of all angles around a point is 360°. 3. **Set up the equation:** The angles 94°, $b$, and 243° together make a full circle, so $$94 + b + 243 = 360$$ 4. **Simplify the equation:** $$94 + 243 + b = 360$$ $$337 + b = 360$$ 5. **Solve for $b$:** $$b = 360 - 337$$ $$b = 23$$ 6. **Conclusion:** The measurement of angle $b$ is 23°.