Matrices & Systems · Medium problem

Each quarter, a company reshuffles its staff among Sales, Marketing and Support. Of Sales staff, $70\%$ stay in Sales, $20\%$ move to Marketing and $10\%$ move to Support. Of Marketing staff, $15\%$ move to Sales, $75\%$ stay, and $10\%$ move to Support. Of Support staff, $5\%$ move to Sales, $5\%$ move to Marketing, and $90\%$ stay. This quarter there are $300$ Sales, $200$ Marketing and $100$ Support staff. How many people will be in Sales next quarter?