How to determine if a side length represents a right triangle?

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 (%)

Put the equation in slope intercept form by solving for y

What is the solution to the system of equation graphed belowa.(0,-4)b.(2,5),1),-3)