What is 7.09 x 10^5 - 6.10 x 10^4 in scientific notation

If you want to subtract them in scientific notation, first you need to make both exponents equal. One of them is raised to 5 and the other is raised to 4. 

x 

x  

To make the first one raised to four, all you need to do is move the decimal to the right. The new notation will then be:

x 

Now all you need to do is line up the decimals like you would normally and then subtract. Also copy the

x 
- x  
=
x 

Then we to make it in standard form, just move the decimal to the left and add 1 to the exponent. 

x 
 

Most likely a is the answer - because  you generate   38 atp's but also consume an atp.   each atp gives approx. less than 4 kcal so probably a is the closest answer.

True, the standard unit for volume is liters which can be represented by either a lower case "l" or a capital "l"