Answer:
We must add 400 ml of water.
Step-by-step explanation:
We can use the following equation:

Where:
- C(i) is the initial concentration of the solution (80%)
- C(f) is the final concentration of the solution (30%)
- V(i) is the initial volume (150 ml)
- V(f) is the final volume
Now, we just need to solve the equation for V(f).



Therefore, we must add 400 ml of water.
I hope it helps you!
The number with the same value will be 40 because 10 tens make 100 and 4 tens make 40 so it wili be 140
Question 1: h+4= how many kids in history class.
I think this cause it says to represent the # of kids in the English class with the varible h. there are 4 more kids in the history class for you just add four to the English class( h). this may be wrong tho
question 2: 57+4= 61.
you just input the 57 where the h (# of kids in English class) cause it need to figure out how many are in history and their are just four more kids. I think
also sorry if I suck at explaining things, this makes sorta sense
None of these is correct.
-4(5-x)
= (-4•5) + (-4•-x)
= -20 + 4x
= 4x-20