Answer:
The speed is equal to 
Step-by-step explanation:
we know that
The speed is equal to divide the distance by the time
Let
x------> the distance in miles
y-----> the time in hours
s----> the speed in mph
so

In this problem we have


substitute

We can't see the rectangular prism...
the answer is 10:20.
Hint for the future: be sure to write in the full problem. I only knew the answer because I had to do it myself, but people need more context if they are going to help you.
One formula for the lateral area is
A = 2(LW + H(L+W))
Filling in the given numbers, you have ...
A = 2((5.6 in)·(4.3 in) + (10 in)·(5.6 in + 4.3 in))
= 2(24.08 in² + 99 in²)
= 246.16 in²