Amotorboat, that has speed of 10 km/hour in still water, left a pier traveling against the current of the river. forty-five minutes after the boat left the pier, the motor of the boat broke, and the boat began drifting with the current. after three hours of drifting with the current, the boat was back at the pier where it had started. what is the speed of the current of the river?

2 km/h

Step-by-step explanation:

Let c represent the speed of the current of the river in km/h. Then the speed of the boat upstream is (10-c). In 3/4 hour, the distance traveled upstream is ...

... distance upstream = (3/4)·(10 -c)

The time taken to travel the same distance downstream is given as 3 hours. The speed in that direction is c, so we have ...

... 3 = distance upstream/c = (3/4)(10 -c)/c

Multiplying this equation by 4c, we get ...

... 12c = 3(10 -c)

... 15c = 30 . . . . . . . . add 3c

... c = 2 . . . . . . . . . . . divide by 15

The speed of the river current is 2 km/h.

it would be 6xy and -16xy.

step-by-step explanation: so we look at the formula un = a + (n-1)d

un is the amount of seats

n is the nth term aka row number

a is the original sequence/row number

d is the difference between each term

so in this a=22 d=6 and n can remain as n because we are simply formjng a rule

lets put these in the equation

un=22+(n-1)(6)

this is your answer to part a

however

lets double check that this is correct, we'll try putting it into the second term

un=a+(n-1)d

u2=22+(2-1)(6)

u2=22+6

u2=28

as the question said the second row has 28 seats so now we know the formula we made is correct.

as for part b

un=a+(n-1)

its asking us to find a row with 100 seats.

remember un was the amount of seata so all we do is substitute this in.

un=100 a=22 d=6

un=a+(n-1)d

100=22+(n-1)(6)

so now we simplify to find n which is the row number.

100-22=22+(n-1)(6)-22

78=(n-1)(6)

78/6=(n-1)(6)/6

13=n-1

13+1=n-1+1

14=n

so now we know that in the 14th row there is 100 seats.

hope this and that you understood! its my first time using the app or anyone out on here : p its also me to revise so a bunch! ask more questions if you dont understand ☺