so did you get what I solved the answer is D ok
2.6 • 10^10 = 26,000,000,000
4.94 • 10^13 = 49,400,000,000,000
49,400,000,000,000/26,000,000,000= 1900
And adult had 1900 times more cells than a newborn. Or if you want to put it in scientific notation it would be 1.9 • 10^3
the reciprocal is 15 by 12