Answer:

Step-by-step explanation:
Remember that

Let
x ----> the total cost of the books
we know that
The total cost of the book multiplied by 0.65 must be equal to $438.75
so
The linear equation that represent this situation is

solve for x

Each term is 4 times the previous one.
The answer to the question
Since they are similar triangles, they are just enlarged versions of each other. This means that the left-most angle of triangle XYZ is also 35°.
Angles in a triangle add up to 180°, so we can find the missing angle by subtracting the two known angles from 180.
180 - 70 - 35 = 75
The right-most angle of triangle XYZ would be 75°.
Hope this helps!