Solve each equation by completing the square. if necessary, round to the nearest hundredth.
show steps, steps needs.
1. b^2+10b=75
2. n^2-20n=-75
3.. t^2+8t-9=0
4. m^2-2m-8=0
5. v^2+4v-2=0

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?