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IM: 7.5.14: Solving Problems with Rational Numbers (Lesson)

By Newsela Staff
Last updated 6 days ago
8 Questions
14.1: Which One Doesn’t Belong: Equations

Which equation doesn’t belong?

14.2: Draining and Filling a Tank
A tank of water is being drained. Due to a problem, the sensor does not start working until some time into the draining process. The sensor starts its recording at time zero when there are 770 liters in the tank.

Given that the drain empties the tank at a constant rate of 14 liters per minute, complete the table:

Later, someone wants to use the data to find out how long the tank had been draining before the sensor started. Complete this table:

If the sensor started working 15 minutes into the tank draining, how much was in the tank to begin with?

14.3: Buying and Selling Power
A utility company charges $0.12 per kilowatt-hour for energy a customer uses. They give a credit of $0.025 for every kilowatt-hour of electricity a customer with a solar panel generates that they don't use themselves.

A customer has a charge of $82.04 and a credit of -$4.10 on this month's bill.

What is the amount due this month?

How many kilowatt-hours did they use?

How many kilowatt-hours did they generate that they didn't use themselves?

Find the value of the expression without a calculator.

(2)(-30)+(-3)(-20)+(-6)(-10)-(2)(3)(10)

Then, write an expression that uses addition, subtraction, multiplication, and division and only negative numbers that has the same value.