Helmut can paddle in still water at a speed of 4 km/h. If he paddled 10 km upstream against the current and then paddled 10 km back downstream with the current, and the total trip
took 9 h, what is the speed of the current?

please help

-50/3 is the final answer! : )

answer: they are supplementary angles

step-by-step explanation: 161+19=180. supplementary angles equal 180 degrees

system of linear equation

step-by-step explanation:

as given in the data

a= 20 , b= -12

let us suppose that it is a straight line equation

now we know the formula for the system of linear equation

b= ma + c )

here m is slope of a straight line which is equal to formula

m=   (ii)

and here c is a constant

now putting the value of a and b in equation (ii)

m=

m=

putting the value of a,b and m in equation (i) gives us

-12 = + c

-12=-12 + c

adding 12 to both sides

-12 +12 = -12 +12 +c

0 =c

or c=0

as the value of the constant is zero which gives us that it is a linear equation and this order pair satisfies the system of linear equations.

the answer is a and d