Nova, Luna, and Emek prepared their lander for its descent to the Moon. The lander had 4 identical fuel tanks. After 36 liters of fuel had been used during the approach, the display showed 244 liters remaining. They let x represent the amount originally loaded into each tank and wrote 4x - 36 = 244. Luna added 36 to both sides to get 4x = 280. Emek divided by 4 and found x = 70 liters. Nova checked that 4(70) - 36 = 244. With 70 liters originally loaded in each tank, the fuel plan was correct, and they began the landing.
Challenges
Challenge 1 of 5
Challenges
Challenge 1 of 4
Hint
Think about the operation being done to 4x and which opposite operation will undo it.
Emek says the first step in solving 4x - 36 = 244 should be to subtract 36 from both sides. Which statement correctly checks his idea?
Emek is correct because 36 should always be subtracted first.Emek is correct because subtracting 36 gives 4x = 208.Emek is not correct because 4 should be added to both sides first.Emek is not correct because adding 36 to both sides undoes the subtraction of 36.Correct! Adding 36 to both sides undoes the subtraction of 36.
Try again. To undo subtracting 36, use the opposite operation on both sides.
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Hint
Write 4x - 52 = 228. Undo the subtraction first, then divide by 4.
Suppose the lander still had 4 identical fuel tanks, but 52 liters were used and the display then showed 228 liters remaining. How many liters were originally loaded into each tank?
Correct! Each tank originally held 70 liters.
Try again. Add 52 to the remaining fuel, then divide the total among the 4 tanks.
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Hint
Replace x with 70 in the original equation without changing any operations.
Nova wants to verify that x = 70 is the correct solution to the story's equation 4x - 36 = 244. Which calculation provides the correct check?
4(70) + 36 = 3164(70) - 36 = 2444 + 70 - 36 = 3870 - 36 = 34Correct! Substituting 70 makes the left side equal 244.
Try again. Substitute 70 for x in 4x - 36 and keep the original operations.
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