Help me solve for the mean pls

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 (%)

Find the value of x. give reasons to justify your solutions! l, m ∈ kn

There are a total of 75 students in the robotics club and the science club. the science club has 11 more students than the robotics club. how many students are in the science club?