5 4 10b b 6 ?

5a 2a 40 2 2 5c

The above numbers are presented in 3 sets of 4 boxes each.
What is the missing algebraic expression in the box in the last set?

To find the missing algebraic expression in the last set, we can observe the pattern and logic between the given numbers in the boxes.

In the first set:
5 is related to 5a (multiply by a)
4 is related to 2a (multiply by 2)

In the second set:
10b is related to 40 (multiply by 4)
b is related to 2 (multiply by 2)

From the given pattern, we can see that each number in the second set is obtained by multiplying the corresponding number in the first set by a constant factor.

Using the same logic, we can determine the missing numbers in the third set:
6 is related to 2 (multiply by 2)
? is related to 5c (multiply by c)

Therefore, the missing algebraic expression in the box in the last set is 5c.