Here are two stories: The initial freshman class at a college is 10% smaller than last year’s class. But then during the first week of classes, 20 more students enroll. There are then 830 students in the freshman class. A store reduces the price of a computer by $20. Then during a 10% off sale, a customer pays $830

here are two equations: 0.9x+20=830, 0.9(x-20)=830

A. Decide which equation represents each story.

B. Explain why one equation has parentheses and the other doesn't.

C. Solve each equation, and explain what was the solution means in the situation.

Thank you to the people that answered my questions!

hola hablas español

answer: the common difference is -0.10

for the friend request.

when a figure, such as triangle (xyz) is reflected over the line y = x to create x'y'z' the x-coordinates and y-coordinates of the original image (pre-image) will be reversed for the image. (e.g., (x, y) > (y, x)) this means that the pre-image position of the x- and y-coordinates switch places which in turn provides a mirror like image of the original xyz.  

i notice that when i draw a line segment from x to x', that the points are parallel from each other -- they are exactly across from each other and do not intersect with any other points.  

yes, think i would see the same characteristic if you drew the line segment connecting y with the reflecting line and then y' with the reflecting line because of the essence of reflections. because it is a mirror image, each point was effected the same way which leads me to conclude that they same would apply to y and y'.