In 2 hours (x) Frank earned $31(y). In 4 hours he earned $62

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 (%)

If sin(x) = 0 and cos(x) = 1, what is tan(x)?

Express -5 2/5 as an improper fraction.