Question

a hot air ballon was at 2,180 feet. it decended at 120 feet per minute for 9 minutes. what is the balloons new height?

Answer 1

The balloons new height is
`1,100\ ft`

Explanation:

Let

x ----> the number of minutes

y ----> the height of a hot air balloon in feet

we know that

The linear equation in slope intercept form is equal to

`y=mx+b`

where

m is the slope or unit rate

b is the y-intercept or initial value

In this problem we have

The slope is equal to

`m=-120\ ft\ per\ minute` ---> is negative because is a decreasing function

The y-intercept is equal to

`b=2,180\ ft`

substitute

`y=-120x+2,180`

For x=9 minutes

substitute in the linear equation

`y=-120(9)+2,180`

`y=1,100\ ft`