Mrs. Smythe = x
Daughter = y
x = 2y
(x - 10) + (y - 10) = 46
x - 10 + y - 10 = 46
x + y - 20 = 46
x + y = 66
Put 2y in for x
2y + y = 66
3y = 66
y = 66/3
y = 22
The daughter is 22
The mother = 44
Answer: The ball will hit the ground 4 seconds after being thrown.
Step-by-step explanation:
By definition, the ball hits the grounds when the height is zero.
Then, knowing that the Quadratic function that models that situation is:

You can make it equal to zero:

Now you can use the Quadratic formula:

In this case you can identify that:

Therefore, knowing these values, you can substitute them into the Quadratic formula and then evaluate, in order to find the solution:

Choose the positive solution.
Then, the ball will hit the ground 4 seconds after being thrown.
Numbers with negative numbers become smaller such as decimals. Numbers with positive exponents become bigger in quantity