The square of the quantity 18 less than x

Select all the statements that apply to this figure

If tan2a=cot(a+60), find the value of a, where 2a is an acute angle

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?