What is the following number in decimal form? 1.68 × 10 –8
a. 0.168
b. 0.168
c. 168,000,000
d. 16,800,000,000

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?