Please answer this I'm really confused and need help

What term makes it inconsistent y=2x - 4

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 (%)

Maria solved an equation as shown below. what is the solution to maria’s equation?