Let's assume
boiling point is y
altitude is x
we are given
This relationship between altitude and boiling point is linear
At an altitude of 1000 feet, water boils at 210°F
so, first point is (1000,210)
so, x1=1000 , y1=210
At an altitude of 3000 feet, water boils at 206°F
so, second point is (3000,206)
so, x2=3000,y2=206
now, we can find slope

now, we can plug values


now, we can use point slope form of line

so, we can plug it

so, point slope form of line is

now, we can plug x=8000
and then we can solve for y


So,
the boiling point of water at an altitude of 8000 feet is 196°F..........Answer