Given :
Rain is falling at 0.5 inches per hour and 1.5 inches have already accumulated.
To Find :
How many hours must have passed if there are 5 inches of rain .
Solution :
Let , after x hours rain accumulated is 5 inches .
We know , general equation of line :
y = mx +c
Here , m = 0.5 and c = 1 .
So , equation of rain accumulated is :
Now , putting value of x = 5 hours .
We get :
Hence , this is the required solution .