4*d^(-3)*d^18 = 4*d^(18-3) = 4*d^(15). The trick here is to combine the exponents.
Another way to write this problem would be:
4*d^18
---------- . Here d^18 divided by d^3 results in d^15, so again the final
d^3 answer is 4*d^15.
2) -6
8 is positive and 14 negative. You can either draw a number line and help yourself with that or since the negative one is bigger you can do the subtraction 14 - 8 and then change the sign of the answer.
1/the rate of leakage per hour
This will give you the time it takes for 1 gallon to leak out in hours.
For example, if something is leaking at the rate of 12 gallons per hour, it will take 1/12 of an hour for 1 gallon to leak out. ( or 5 min)
The minimum number of train cars needed is 8 because 112 multiplied by 8 is 896 which means 7 trains will be full and the last one will only carry 108 crates
