SOLUTION: A student must leave for campus in 10 minutes or he will be late for class.​ Unfortunately, he is snowed in. He can shovel the driveway in 20 ​minutes, and his brother

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Question 1083155: A student must leave for campus in 10 minutes or he will be late for class.​ Unfortunately, he is snowed in. He can shovel the driveway in 20 ​minutes, and his brother claims to be able to do it in 12 minutes. If they shovel​ together, how long will it take to clear the​ driveway? Will this give enough time for the student to get to the​ campus?
Found 2 solutions by josmiceli, josgarithmetic:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Add their rates of shoveling to get their
rate shoveling together
student's rate:
[ 1 driveway shoveled / 20 min ]
brother's rate:
[ 1 driveway shoveled / 12 min ]
--------------------------------
Let +t+ = their time to shovel the
driveway working together
+1%2F20+%2B+1%2F12+=+1%2Ft+
Multiply both sides by +60t+
+3t+%2B+5t++=+60+
+8t+=+60+
+t+=+7.5+
They can shovel the driveway in 7.5 min, which
is less than 10 min needed

Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
1%2F20%2B1%2F12=3%2F60%2B5%2F60=8%2F60, as if 8 driveways cleared in 60 minutes; or 4%2F3 driveways-worth cleared in 10 minutes.

The student will be late. He needs 10 minutes to travel for being on-time to campus. Time t, to clear the driveway by student and his brother combined will be %288%2F60%29%2At=1
t=60%2F8
t=15%2F2
t=7%261%2F2------seven and a half minutes;
which leaves the student only 2.5 minutes of travel time before he will no longer be to campus on-time.