I will take 4 hours for it to be be 12 inches above its flood stage
Area of triangle = 1/2 x base x height
so old triangle we have 1/2 x b x h = 48
new triangle has base 3 times as long and height is half as long
so we would get:
1/2 x (3B) x (1/2H) = area
rewrite as 1/2 x 3/2 x b x H = area
divide by original are os 1/2 x b x h and you end up with 3/2
so new area = 3/2 x old area
new area = 3/2 * 48 = 72 square inches
68-40=28
28/4=7
therefore, 7 is your answer
(Hope it helps my friend ^_^)
ANSWER
EXPLANATION
We want to simplify
We multiply the first fraction by the reciprocal of the second fraction to obtain,
We cancel the common factors to get,
This gives us,