Answer:
im guessing the answer is 43.7
Step-by-step explanation:
Answer:

Step-by-step explanation:
In order to add or subtract numbers in scientific notation, the powers of ten must have the same exponent. In this caes the diameter of an average human body cell is a power of -4 and the diameter of a plant cell is a power of -3. In order to add them, we can move the decimal over for the body cell diameter:

Add the two values: 
To find distance, subtract the largest number from smaller
41 - (-7)
41 + 7 = 48
the distance is 48
hope this helps
Alexander has to miles to go because if one mile is a third you can simply maltiply by three, then subtract the mile he already went. you maltiply by three because it was a third of the way there