I need help asap! math problem

Solve the system of equations using the linear combination method. {4x−3y=127x−3y=3 enter your answers in the boxes.

Ateacher wanted to buy a chair, a bookshelf, two tables and a desk. she spent $900 for all five items and the chair and the desk combined 70% of her total. if the bookshelf cost $50, how much did each of the tables cost?

Is the number 128.439 a rational number