Look at the first person’s answer. Cause I know I’m wrong
The concept required to solve this problem is the optical relationship that exists between the apparent depth and actual or actual depth. This is mathematically expressed under the equations.

Where,
Depth of glass
Refraction index of water
Refraction index of glass
Refraction index of air
Depth of water
I enclose a diagram for a better understanding of the problem, in this way we can determine that the apparent depth in the water of the logo would be subject to



Therefore the distance below the upper surface of the water that appears to be the logo is 4.041cm
Answer:

negative sign indicates that the distance is decreasing with time
Explanation:
Let at any time t after noon that is 12 p.m.
distance traveled by car A = 40t
distance traveled by car B = 90-60t
then distance between the two cars at time t
............1
also, at time 1 p.m.
distance 
D=50 Km
differentiating equation 1 w.r.t. t we get

put t= 1 and D= 50 we get

