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: 
If the internet doesn't know then the question isn't even real
The major arc DGF and the minor arc FD both make up the circle, so their measures should add to 360°.
(arc DGF) + 153° = 360°
arc DGF = 207°
Answer:
5 (5x1) , -10 -(5x2), 20(10x2), -40 -(20x2), 80(40x2)
so the next number should be previous number in the sequence multiplied by 2 and a negative sign.
-`(80x2) = -160
