Can someone please help me with math.

Add the two expressions 3.8b - 7 and 2.9b + 9 enter your answer in simplified form

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

How many solutions does the nonlinear system of equations graphed below have? a. one b. zero c. four d. two