Answer:
The chemist needs to add 400mL of 40% solution.
Step-by-step explanation:
The equation

gives the percent concentration
of the final mixture, when
mL of the 40% solution are added.
Now we are asked, how many milliliters
of the 40% solution should the chemist add to get final percent concentration
; this is just a matter of solving the equation

and we solve it the following way:

Thus, the chemist needs 400mL of 40% solution to get 30% concentration of the final mixture.
Answer: i don't know
Step-by-step explanation:
Answer:
deze nuts thanks u
Step-by-step explanation:
<h3>
Answer: 64 cm^2</h3>
Reason:
The parallelogram has area of A = base*height = 10*7 = 70 cm^2
The white rectangle has area of B = base*height = 3*2 = 6 cm^2
The shaded region has area of A - B = 70 - 6 = 64 cm^2
If you are curious why the rectangle and parallelogram use the same formula to get the area, notice how you can move that triangle on the left toward the right side so that a rectangle can be formed.