The answer to the first part is 172 plants per row with a remainder of 3 plants
The answer to the second part is, Martin knows that 7 goes into 700 100 times, 7 goes into 490 70 times, and 7 goes into 17 twice with a remainder of 3. He then adds 100 70 and 2 together to get 172 with a remainder of 3.
