This would simplify to 6.60 meters/second.
6b-18c+18x is simplified for you
First make an equation for first tree
Y=2x+50
Then second tree
Y=1x+59
Then put them equal to eachother
2x+50=1x+59
Solve by subtracting 1x and then subtracting 50
Answer= x=9
9 months