Hurry ill pick ! melinda and paul 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 paul shoveled for 25 minutes to complete 345 square feet of driveway. 30x + 30y = 450 20x + 25y = 345 how much more can paul 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

30x + 30y = 450 20x + 25y = 345

Here 345 represents the total area (in sq ft) shoveled; x repres. Melinda's rate and y represents Paul's rate.  We need to solve for x and y and then subtract the smaller from the larger.

30x + 30y = 450   Multiply this eqn by 2:      60x + 60y = 900
20x + 25y = 345   Mult this eqn by -3:          -60x -75y  = -1035
                                                                   
                                                                              -15y  = -135
                                                                                    y = 9

This comes to 9 square feet per minute.
Now, let's find x:    30x + 30y = 450; 30x + 270 = 450; 30x = 180; x = 6

Melinda can shovel 6 sq ft in 1 min, whereas Paul can shovel 9.

The difference is (9 - 6) sq ft / min,     or     3 sq ft / min   (answer)