Atrain can hold 78 passengers. the train starts out empty and picks up one passenger at the first stop,2 passengers at the second stop,3 passengers at the third stop, and so forth. after how many stops will the train be full.

After the 12th Stop

Step-by-step explanation:

2nd stop 1+2=3

3rd 3+3=6

4th 6+4=10

5th 10+5=15

6th 15+6=21

7th 21+7=28

8th 28+8=36

9th 36+9=45

10th 45+10=55

11th 55+11=66

12th 66+12=78

After the 12th stop.

-362

step-by-step explanation:

(12)(4)+2(12)-34(12)+2(12)-3

  \/         \/         \/         \/

  48 +   24 -   408 + 24 - 3

      \   /               \   /

          72     -     432 - 3 = -363

18.75 gallons

step-by-step explanation: