Section C Section C Checkpoint

Problem 1

Solve each equation.

  1. a+6.5=-3.2a + 6.5 = \text-3.2
  2. -4b=30\text-4b = 30
Show Solution
Solution
  1. a=-9.7a = \text-9.7
  2. b=-7.5b = \text-7.5 (or equivalent)
Show Sample Response
Sample Response
  1. a=-9.7a = \text-9.7
  2. b=-7.5b = \text-7.5 (or equivalent)

Problem 2

Choose the equation that best represents the situation:

An elevator is descending at a rate of 2.5 feet per second. How long will it take the elevator to go down 20 feet?

A
$20 - x = 2.5$
B
$x + 2.5 = \text-20$
C
$20 \div \text-2.5 = x$
D
$\text-2.5x = \text-20$
Show Solution
Solution
$\text-2.5x = \text-20$
Show Sample Response
Sample Response
$\text-2.5x = \text-20$

Problem 3

A scientist is using a drone to explore a cave. Over a period of 6 seconds, the drone goes from 25 feet below the surface to 16 feet below the surface.

  1. How fast is the drone moving upward?
  2. At this rate, when will the drone be 5 feet above the ground?
Show Solution
Solution
  1. 32\frac32 feet per second (or equivalent), because -16−-25=9\text-16 - \text-25 = 9 and 9÷6=329 \div 6 = \frac32
  2. in 14 seconds, because 5−-16=215 - \text-16 = 21 and 21÷32=1421 \div \frac32 = 14
Show Sample Response
Sample Response
  1. 32\frac32 feet per second (or equivalent), because -16−-25=9\text-16 - \text-25 = 9 and 9÷6=329 \div 6 = \frac32
  2. in 14 seconds, because 5−-16=215 - \text-16 = 21 and 21÷32=1421 \div \frac32 = 14