Pls help I would appreciate it :))

Can someone me and plz do the problem

Idon’t understand! use slope intercept form to solve: through: (2,5) slope= undefined

Jada has a meal in a restaurant she adds up the prices listed on the menu for everything they ordered and gets a subtotal of $42.00. when the check comes, it says they also need to pay $3.99 in sales tax. what percentage of the subtotal is the sales tax