Help Me Please A repairman charges an inspection fee plus $20 per hour. A customer
with a coupon for 40% off the inspection fee pays $110 for a 4-hour repair.
How many hours are worked when a customer pays $90 without a coupon?

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 (%)