C. 75. The median is the middle number in the sequence
Just add the two equations together.
2b = 18
b = 18/2
b = 9
9 = k + 10
9 - 10 = k
k = - 1
To solve for this we will follow PEMDAS to arrive at the correct answer so we have the following:

Based on calculations the correct answer is A
5+25=48 becase you add 12 each time