What is 0.42857142857 in fraction form without putting it over 1, 10, 100 etc.?

Simplify the expression. -2/5(10+15m-20n)

Acompany that manufactures and sells guitars made changes in their product range. from the start they had 20 models. then they reduced the number of models to 15. as a result, the company enjoyed a 10% increase in turnover. - how much did the stock level change? in (%)

With alll of except for the 2 that i did already