Recall your d = rt, distance = rate * time.
b = speed rate of the boat.
c = speed rate of the current.
keeping in mind that, as the boat goes Upstream, against the current, it's speed is not "b", but is really " b - c ", because the current is subtracting speed from it.
likewise, when the boat is going Downstream, because is going with the current, is really going faster at " b + c ".

what is the speed of the boat? well, 61 + c = b.
Tn=n²+3
from 4 to 7....the difference is 3, then from 7 to 12 the difference is 5 and from 12 to 19 the difference is 7
therefore we constantly add 2 to the difference
The fifteenth customer will be the first because 5x3=15
Answer:
252 Cheese Bugers were sold on Thursday
Step-by-step explanation:
378 divided by 3=126
126+126= number of hamburgers
126= number of chese bugers
126+126=252
This is 6P4
the number of permutations of 4 from 6. 6! / 2!
= 6*5*4*3* 2 / 2 = 360