Ms. watson receives a base pay of $150, plus a commission of $45 on each appliance that she sells. her total pay depend on how many appliances she sells.

This is asking for a linear function. The base pay is $150, so even if she sells nothing, she cannot be paid less than $150. Because of this, we make that out y-intercept. The number of appliances sold is a variable, so we make that the "X" and multiply that by the amount made ($45) on each additional item sold. You then follow the Order of Operations (PEMDAS) to make your equation.