Two persons are on either sides of a tower of height 50 m. The persons observers the top of the tower at an angle of elevation of 30° and 60°. If a car crosses these two persons in 10 seconds, what is the speed of the car?

• A. $24\sqrt 3 \,{\text{km/hr}}$$
• B. $\frac{{20\sqrt 3 }}{3}\,{\text{km/hr}}$$
• C. $\frac{{24}}{{\sqrt 3 }}\,{\text{km/hr}}$$
• D. one of these