Which equation represents the relationship between the angles in the figure?

Segments , , and intersect at point , and angle is a right angle. Find the value of .

Select all the expressions that are the result of decreasing by 80%.

Andre is solving the equation . He says, “I can subtract from each side to get and then divide by 4 to get .” Kiran says, “I think you made a mistake.”

1. How can Kiran know for sure that Andre’s solution is incorrect?
2. Describe Andre’s error, and explain how to correct his work.

Solve each equation.

A train travels at a constant speed for a long distance. Write the two constants of proportionality for the relationship between distance traveled and elapsed time. Explain what each of them means.