# A deep sea diver changes his position relative to the surface of the water by #-7/2# meters per minute. How do you write and evaluate an expression to show his position after 3 minutes if he starts at the surface of the water?

##### 1 Answer

The expression for position in relation to time is:

#p = -7/2t#

After 3 minutes, the diver is at

#### Explanation:

In this case,

When we're dealing with position and time, we use the following formula:

#color(limegreen)"position " = color(red)" original position " + color(blue)" speed" xx "time"#

Let's call our new position *original* position is

Let's also call our *time* variable

#color(limegreen)p = color(red)0 + color(blue)((-7/2))t#

#color(limegreen)p = color(blue)(-7/2)t#

Now, to solve for

#color(limegreen)p = color(blue)(-7/2)(3)#

#color(limegreen)p = -21/2#

#color(limegreen)p = -10.5#

So, after 3 minutes, the diver is at

This means that he is **below** the surface of the water.

*Final Answer*