Here are two stories: The first college freshman class is 10% smaller than last year’s class. But then, during the first week of classes, 20 more students sign up. There are then 830 students in the first year class.
A store reduces the price of a computer by $20. Then, on a 10% off sale, a customer pays $830.
Here are two equations:
0.9x+20=830
0.9(x−20)=830
Decide which equation represents each story.
Explain why one equation has parentheses and the other does not.
Solve each equation and explain what the solution means in the situation. Here are two stories: The first college freshman class is 10% smaller than last year’s class. But then, during the first week of classes, 20 more students sign up. There are then 830 students in the first year class. A store reduces the price of a computer by $20. Then, on a 10% off sale, a customer pays $830. Here are two equations: a. Decide which equation represents each story. b. Explain why one equation has parentheses and the other does not. vs. Solve each equation and explain what the solution means in the situation. =what is the answer The computer scenario is the second example. This is the second equation because there is a $20 discount on every computer sold, then an additional 10% is deducted (thus bringing the cost down to 90% of the original cost)
0.9(x – 20) = 830
when solving this, you distribute the 0.9 in parentheses (i.e. multiply it by)
0.9(x) – 20(0.9) = 830
0.9x – 18 = 830
then add 18 to both sides
0.9x – 18 + 18 = 830 +18
and then you finish and solve for x : ) What does the solution mean in the equation