Break 90 into 10 × 9, then divide step by step.<br><br>
&bull; 2.07 ÷ 90 = 2.07 ÷ (10 × 9) = 2.07 ÷ 10 ÷ 9<br>
&bull; 2.07 ÷ 10 = 0.207<br>
&bull; 0.207 ÷ 9 = 0.023<br><br>
Final Answer: First blank = 2.07, second blank = 10, third blank = 9, fourth blank = 0.023