So, Katherine can do 0.1 of the job per hour. (if she needs 10 hours for the job, each hour she can do the whole divided by the time, so 1/10, which is 0.1)
if in two hours she and Marina can be done, then Marina will do 1(the whole job)-2/10 (twice as much as she can do in an hour)=0.8 of the job. So if Marina does 0.8 of the job in two hours, each hour she will do half of it: 0.4 - and this is the correct answer
Answer:
Step-by-step explanation:
Here is how to get 9:
3x = 4(x - 2.25)
Solve 4(x - 2.25)
3x = 4x - 9
Move the variable to the left side and change it's sign
3x - 4x = -9
Combine like terms
-x = -9
change the signs
x = 9
There ya go! I hope this isn't too confusing!
I don’t know why the word “million” is there, but the incremental cost per unit of the secon hundred units is $30 per unit.
