Jim has 2 rows of 4 trees to start.  When he turns 10 he decides to plant a new row of trees every year on his birthday.  On his 15th birthday after he doubles the number of trees he has.  How many trees does he have?
How many trees did Jim start with? ** He started with 2*4=<<2*4=8>>8 trees
How many years does Jim plant trees? ** He plants trees for 15-10=<<15-10=5>>5 years
How many trees did Jim plant? ** So he planted 5*4=<<5*4=20>>20 trees
How many trees did Jim have after planting? ** So he had 20+8=<<20+8=28>>28 trees
How many trees did Jim have after doubling? ** After doubling them he had 28*2=<<28*2=56>>56 trees
#### 56