Help me please .

Carl wants to buy a television that cost $500 including taxes. to pay for television he will use a payment plan that requires him to make a down payment of $125 and then pay $70.50 each month for six months what is the percent increase from the original cast of the television to the cost of the television using a payment plan.

Ijust need to see how to do this. so you don’t have to answer all of them just a step by step explanation of one.

What is the y-intercept of the line given by the equation