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Melinda and Paula shovel driveways and sidewalks in the winter as a way to earn extra money. Together they shoveled 450 square feet of sidewalk in 30 minutes. Then Melinda shoveled for 20 minutes while Paula shoveled for 25 minutes to complete 345 square feet of driveway.

30x + 30y = 450
20x + 25y = 345
How much more can Paula shovel in 1 minute than Melinda?

3 square feet per minute
6 square feet per minute
9 square feet per minute
15 square feet per minute



Answer :

Answer:

3 square feet per minute

Step-by-step explanation:

The equation

30x + 30y = 450

can be divided by 30 to
x + y = 15

If we multiply this by 20:

20x + 20y = 300

This can be subtracted from the second equation yielding:
5y = 45 and therefore y = 9

Next we can calculate x:
345 - 25 * 9 = 120 = 20 * x

From which we derive x = 6

Therefore the difference is 9 - 6 = 3

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