It takes a boat 4 hours to travel downstream 84 miles and 5 hours to travel up stream 55 miles. what is the speed to the boat in still water ? mph what is the speed of the current ? mph

16 MPH boat speed still water

5 MPH current speed

Step-by-step explanation:

84/4 - x = 55/5 + x

x = (84/4-55/5)/2 = 5 mph current speed in MPH

11+5 = 16 is boat speed in MPH

21 MPH downstream, 11 MPH upstream

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional

c

step-by-step explanation: