Answer:
x = 5 , y = 15
Step-by-step explanation:
You can solve this using substitution.
Let the quantity of cheese wafers be denoted by x and the quantity of chocolate wafers denoted by y
2x + 1y = 25
x + y = 20
These two equations are the answer to part A, (remember to include the above prompt which says what x and y denote).
For part B I used substitution because it was more applicable to the question then addition or elimination.
ACTUAL WORK
Set 2x + 1y = 25 equal to x
x = 25 - y / 2
Replace x with y in the second equation
(25 - y / 2) + y = 20
And solve for y
y = 15
Since we know what y is we can replace y in the second equation and find what x is
x + 15 = 20
Solve for x
x = 5
Mrs. Wang is 55 years old and her daughter is 18 years old.
What are we trying to solve?
Answer:

Step-by-step explanation:
In a 30 - 60 - 90 triangle the side opposite the hypotenuse is 1/2 the hypotenuse and which will be the shorter side. Read this over a couple of times till you realize that (x + 12)/2 is the shortest side.
[(x + 12) / 2]^2 + x^2 = (x + 12)^2 subtract [(x + 12)/2]^2 from both sides.
x^2 = (x +12)^2 - [ (x +12)/2]^2
x^2 = (x + 12)^2 [ 1 - (1/2)^2] You were given this as a question in school? It seems awfully hard.
x^2 = (x + 12)^2 [3/4]
4x^2 = 3*(x^2 + 24x + 144)
4x^2 = 3x^2 + 72x + 432
x^2 - 72x - 432 = 0 This is a quadratic, do you know what they are?
The solution to this comes to x = 77.56
I don't think I made a mistake, but it is sure possible.Check the numbers and my method.