A peron work at a vegetable farm and a paddy field. He earn R 200/- per hour from
vegetable farm and R 250/- per hour from paddy field. Lat week, he worked for both job for
a total of 30 hour, and earned a total of R 6900/-. How long did the peron work at the
vegetable farm lat week, and how long did he work at the paddy field?