Question

Each calendar will sell for $5 each write an equatio to model the total income for selling calendars

Answer 1

To answer the question above, I let x be the number of calendars sold. You may use any other letter as this is just for representation. The total income generated in selling calendars is calculated by multiplying the number of calendars with the price. That is,
                                   total income = 5x
If we let total income be y, our equation is further simplified into, 
                                            y = 5x