A chemist has one solution that has 50% acid. She has another solution that is 25% acid. How many liters of the 50% acid solution should she combine to get 10 liters of a 40% acid solution?

Step-by-step explanation:

Let's begin by assigning letters to represent our two unknowns:

   x (liters of 25% solution)

   y (liters of 50% solution)

Our system of equations will consist of two equations:

   Equation #1 (total volume of solution)

   Equation #2 (total concentration of acid)

Our total volume of solution is 10 liters, which can be expressed as the sum of our unknowns:

   Equation #1:  x + y = 10

Our total concentration of acid can be expressed as the sum of the individual acid concentrations to make up the concentration of the final solution:

   Equation #2:  (0.25)(x) + (0.50)(y) =

                            (0.40)(10)

We can use Equation #1 to express one unknown in terms of the other and then plug that expression into Equation #2 to solve for one of the unknowns:

   x + y = 10

         y = 10 - x

Now we'll plug our expression for y in terms of x into Equation #2 and solve for x:

   0.25(x) + 0.50(10 - x) = 0.40(10)

   0.25x + 5 - 0.50x = 4

   -0.25x = 4 - 5

   -0.25x = -1

          x = (-1)/(-0.25)

          x = 4 (liters of 25% solution)

Now we'll plug our value for x into Equation #1 and solve for y:

   4 + y = 10

         y  = 10 - 4

         y = 6 (liters of 50% solution)

Finally, we will verify the correctness of our answers by plugging these values into Equation #2 to see if the sum of the component acid concentrations equals the final solution concentration:

   0.25(4) + (0.50)(6) = 0.40(10)

   1 + 3 = 4

         4 = 4 (our answers are correct)

3< x< 5

step-by-step explanation:

|x - 4| < 1

there are two solutions, one positive and one negative.   remember to flip the inequality when taking the negative solution

x-4 < 1       x-4 > -1

add 4 to each side

x-4+4 < 1+4       x-4+4 > -1+4

x< 5                 x> 3

3< x< 5

a. turk and mcalister

b. howard, mission, and market

c. yes. since streets end some do not cross yet are not parallel to others. example: mcalister and 5th

step-by-step explanation:

parallel lines are lines which do not intersect ever and look a lot like railroad tracks. turk, mcalister and golden gate are examples of these.

intersect are streets which cross each other and a car on one can reach the other. howard, mission, and market intersect with 6th.

skew lines are lines which neither intersect nor are parallel. these lines exist here because some streets end and never intersect another like mcalister and 5th.