If you ever see a big word like greatest,biggest,largest,etc,that stands for Greatest Common Divisor(GCD) and therefore,you have to find prime numbers that can divide the two numbers each equally.
the greatest number of trees Abe can have in each row would be 9
3| 54|27
3 | 18| 9
3|. 6|3
you take the prime factors and multiply which would give you 9
