Solve the system of equations. What is the value for x that makes the system of equations true?

Which three lengths could be the lengths of the sides of a triangle? 21 cm, 7 cm, 7 cm 9 cm, 15 cm, 22 cm 13 cm, 5 cm, 18 cm 8 cm, 23 cm, 11 cm

How do i simply this expression (quadratic formula basis) on a ti-84 or normal calculator?

Susan is paying $0.30 per $100 on her $483,000 home in homeowners insurance annually. if her annual homeowners insurance premium is divided into twelve equal monthly installments to be included on each of her monthly mortgage payments of $2,128.00, what is her total monthly payment?