It should be something along the lines of this:
[tex]x= \frac{y}{5} + 6[/tex]
Where x is the number of tomatoes Nelson is planting this year and y is last year's tomatoes.
Take it with a pinch of salt, 'cause I kinda stink at math, but...
6 more than something would just be adding six to it. And y/5 = (1/5)y. If y/5 isn't available, (1/5)y should be.
