Question 889483
A 3-foot tree is planted, and it grows 4 feet per year.
 If another 3-foot tree is planted two years later but it grows at 5 feet per year, 
how many years after the second tree is planted will it take to catch up to the first tree?
:
let y = number of yrs after the 2nd one is planted, they will be the same ht
:
5y + 3 = 4(y+2) + 3
5y + 3 = 4y + 8 + 3
5y - 4y = 8 + 3 - 3
y = 8 yrs they will be the same
:
:
Check 
5(8) + 3 = 43 ft
4(8+2) + 3 = 43 ft