The ball describes a parabola, as you can see in the attached picture. So, the point where the ball strike the ground is the point where the parabola meets the x axis. In fact, the x-axis is the set of points where y=0, which means that the ball has height 0 or -again- it hits the ground.
So, we have to set y=0 in our equation and look for the positive solution. We have
And the positive solution is
So that's the distance from the child where the ball strikes the ground.
Let 
be the number of liters of the 10% solution to be used, and 
the number of liters of the 4% solution. The chemist wants to end up with a 4 liter solution, so
For each liter used in the mixture, a concentration of either 10% or 4% acid will be contributed, and the goal is to make a 4L solution whose concentration is 7%, which means
Solving for 
gives 
, so 2L of both solutions is needed.
Answer:
Ok where's the fractions?
Step-by-step explanation:
Answer:
40 and 35
Step-by-step explanation:
If we say the first car uses x gallons then the second car must use 75 - x gallons.
The distance travelled is the number of gallons used * the efficiency of the car.
20x + 15(75-x)=1325
20x + 1125 - 15x = 1325
5x = 200
x = 40
This means that the first car uses 40 gallons and the second car uses 75-40= 35 gallons
