4.6 meters per second was her walking speed
Answer:
see explanation
Step-by-step explanation:
If AB is a tangent then ∠ ABC = 90° and Δ ABC is right
Using the converse of Pythagoras' identity
If the square of the longest side is equal to the sum of the squares on the other 2 sides.
15 is the longest side and 15² = 225
9² + 12² = 81 + 144 = 225
Thus Δ ABC is a right triangle at B
Thus AB is a tangent to the circle at B
Answer : x= -4
This type of problem, you set them equal to each other. And then solve. Don’t forget you can multiply each side by denominator to eliminate the fraction.
Work:
Answer: 
Step-by-step explanation:
Let be "x" the original volume of the solution (in milliliters) before the acid was added and "y" the volume of the solution (in milliliters) after the addition of the acid.
Set up a system of equations:

Applying the Substitution Method, you can substitute the second equation into the first equation and then solve for "x":
5x7=35
5x7=5x(5+2)
5x7=(5x3)+(5x4)
5x7=20+15
5x7=35
This is how I would do it :)