For number 1, theat is not a right triangle as a squared plus b squared does not equal c squared
Answer:
The speed is still water is
.
Step-by-step explanation:
Dimentionally speaking, speed is distance divided by time. Since, the person is travelling downstream, absolute speed is equal to the sum of current speed and speed of the person regarding current. Both components are constant. That is:

Where:
- Current speed, measured in miles per hour.
- Speed of the person regarding current, measured in miles per hour.
- Distance travelled downstream, measured in miles.
- Time spent on travelling, measured in hours.
Speed in still water occurs when current speed is zero. Then, such variable is obtained after subtracting current speed on both sides of the expression. Hence:

The speed is still water is
.
Step-by-step explanation:
y=-2x+1 so we say (-2x+1)
we flip the equation by saying
-2x+1 -1=y+-1
-2x=y-1
Divide both sides by -2
-2÷-1 = y-1÷-2
so x=-1÷2 y=+1÷2
To solve your question, you add all of the measurements together, set them equal to 180, solve for x, and plug x back in for whichever angle they are asking for; in this case, they want angle R
7x + 12x + 20 + 20x - 35 = 180
39x - 15 = 180
39x = 180 + 15
39x = 195
x = 5
Angle R = 12x + 20
12(5) + 20
60 + 20
80
Option C is your answer.