well, we know his rate is 6/5 lawns/hour that means he can do 6 lawns in 1 hour, well, how many can he do in 50 hours?
[tex]\bf \begin{array}{ccll} lawns&hours\\ \cline{1-2} 6&5\\ x&50 \end{array}\implies \cfrac{6}{x}=\cfrac{5}{50}\implies \cfrac{6}{x}=\cfrac{1}{10}\implies 60 = x[/tex]
