The water level of a river is 170 feet. the river recedes 4 feet each year. ingrid claims that the equation that represents this scenario is y = 170x – 4. is her equation correct? explain.

1. y=f(x)=170x-4 is a function with variable x representing a year.

2. Let's consider the difference between 2 consecutive years, say year 3 and year 4

f(3)=170*3-4
f(4)=170*4-4

we expect f(3)-f(4) to be 4 since after 4 years, the water will be 4 feet less than after 3 years.

check: f(3)-f(4)=(170*3-4)-(170*4-4)=170*3-4-170*4+4=170*3-170*4=170*(3-4)=170*(-1)=-170

21.00 per mile and plus 5.50 is 26.50 i think that im pretty sure it is right