Answer:
1 year.
Explanation:
First set up the equation for each tree
Tree A = 6 + 18x
Tree B = 3 + 21x
Since we want to find how long it would take the tree to be same height just set the equation equal to each other.
6+18x = 3+21x
Now you can just solve it by isolating x.
First, subtract 18x from both sides so that we can have just one x and coefficient.
6 = 3 + 3x
Then, subtract 3 from both sides to isolate the x.
3 = 3x
Next, divide both sides by 3.
1 = x
X means the years and so that means it would take just 1 year for the trees to be same height.