Which situation CANNOT be represented by this equation? 
 −13+15=9
3 of the following are correct. Which one isn’t. 
The water level in a tank measures 15
15
 inches and is decreasing every 13
1
3
 of a minute.
At what rate, 
x
, does the water level need to decrease per minute to reach a depth of 9
9
 inches?
The water level in a tank measures 9
9
 inches and is rising 13
 of an inch every minute.
How many minutes, 
, will it take for the water level to measure 
15
 inches deep?
The water level in a tank measures 15
15
 inches and is decreasing 13
1
3
 of an inch every minute.
How many minutes, 
x
, will it take for the water level to measure 9
9
 inches deep?