Suppose you add x liters of pure water to the 10 L of 25% acid solution. The new solution's volume is x + 10 L. Each L of pure water contributes no acid, while the starting solution contains 2.5 L of acid. So in the new solution, you end up with a concentration of (2.5 L)/(x + 10 L), and you want this concentration to be 10%. So we have

and so you would need to add 15 L of pure water to get the desired concentration of acid.
43 total movies the type of movies is added in to confuse you pay no ttention just add the total. he keeps 8 of them
43 - 8 = 35
he gives them to 5 friends
35 DIVIDED by 5 = 7
each friend would get 7 each
Answer:
x= 21
y= 3
z= 21
Step-by-step explanation:
Let the center be O,
=> Triangle AOD is an Isosceles triangle so AO≅DO, "21 = x"
=> Line AC is divided in two equal parts by the center so if AO= 21 then
7y = 21, and thus "y = 3"
=> BOC is also an Isosceles triangle so CO ≅ BO, if CO = 21 (7y → 7*3) then so will be BO. Therefore "z = 21"