78 * 40 show your work because i need to figure out how to do multiplication like this the long way !

3120

Step-by-step explanation:

step 1:multiply 8 with 0 and 7 with 0

step 2:add a 0 in the end and multiply 8 with 4 . you get 32. take 2 and carry over 3. multiply 7 with 4. you get 28 . add 3 you get 31. now add. you get 3120

three-fourths of an hour

36÷48=0.75

0.75=

step-by-step explanation:

12: 00 p.m. to 7: 00 p.m. is a total of 7 hours.

4: 00 p.m. to 7: 00 p.m. is a total of 3 hours.

this means that from 4: 00 p.m to 7: 00 p.m. this represents 3/7 of what was lost from 12: 00 p.m. to 7: 00 p.m.

after knowing this, after doing 11,600 - 6,800 = 4,800

4,800 represents 3/7 of what was lost for 7 hours.

we then divide 4,800 by 3 which gets 1,600.

because we know that 1,600 represents 1/7 of how much water was lost, we just have to multiply by 7, which gets 11,200.   after adding 11,200 to how much water was left at 7: 00 p.m. which was 6,800. 11,200 + 6,800 = 18,000

this means that the pool originally had 18,000 gallons in the pool.

you can also check your work by doing 18,000 - 4(1600), which becomes           1800 - 6400 which gets you 11,600.