it take him 90 hrs to plow 60 acres
Answer:
I think its - 2/3
Step-by-step explanation:
Please find attached photograph for your answer.
Answer:

Step-by-step explanation:
The equation of line in the form .
y = mx + c
Where m is the slope and c is the y- intercept .
As given
The lines y=3x-1 and y=ax+2 are perpendicular .
Here 3 is slope for equation of line y=3x-1 and a is slope for equation of line
y=ax+2 .
Now by using properties of the perpendicular lines property .
When two lines are perpendicular than slope of one line is negative reciprocal of the other line .
Thus

Therefore 
I = / r where I = current and r = resistance
80 = k / 50 so
k = 400
so we have I = 400/r
when r = 40
I = 400/40 = 10 amps