Answer: 8 1/4 inches tall.
Explanation:
When we add the 3/4 + 6/4, since the denominators are the same, we can just add the numerators and leave the denominator alone: 3/4 + 6/4 = 9/4 which is also 2 1/4.
The total height of the plant is 6 + 2 1/4 = 8 1/4 inches tall.