Answer:
x = 20
Step-by-step explanation:
The three angles make up a straight line.
A straight line has 180 degrees.
x + 3x + 100 = x80 Combine
4x + 100 = 180 Subtract 100 from both sides
4x = 180 - 100
4x = 80 Divide by 4
x = 80/4
x = 20
Because you add both negative x’s which is -2 and add the -6 in the right side so then it’s -2x=4
Divide and you get x=-2
90 books would be left I believe I just took 250/9 since it would take 9 quarters to make $2.50 and since 75% was gone that would mean 25% is left so your answer is 90 unless it’s not but I believe it’s right.