Round 463,751 to the nearest hundred

At a local museum, the total price for one adult and one child is $11. mrs. smith paid for herself and her three children. she spent $19. record the system of equations to be solved and then find the price of an adult and child ticket using either elimination or substitution.

Ineed with question three. i don't understand how i'm supposed to achieve 3 marks.

The sum of four times a number and three is two times the number minus twenty nine