Answer:
The Piece of Space Junk travels 18 miles in 30 seconds.
Step-by-Step explanation of how your Teacher Wants you to Do It:
The equation 3 = 5X Demonstrates the idea that for every 5 seconds the space junk moves 3 miles.
Then the equation Y = 30X would demostrate the idea that for every 30 seconds the space junk moves Y miles.
Therefore we have two equations:
3 = 5X
Y = 30X
We can solve for X on equation 1 and plug it into equation 2 to get Y.
3/5 = X
Y = 30(3/5) = 18
Therefore the Piece of Space Junk travels 18 miles in 30 seconds.
Step-by-Step explanation Short Cut:
30 is divisible by 5.
Therefore take 30/5 = 6 and recognize that the junk will travel 3 miles in 5 seconds 6 times.
So 3 x 6 = 18.