7 1/ 2 - [ 2 1/ 4 ÷ { 1 1/ 4 - 1/2(1 1/ 2 - 1/3 - 1/6)}] is equal to?

Given expression = 15/2 -[9/4 ÷ {5/4 - 1/2(3/2 - 1/3 - 1/6)}]
= 15/2 -[9/4 ÷ {5/4 - 1/2 x 1}]
= 15/2 -[9/4 ÷ {5/4 - 1/2}]
= 15/2 -[9/4 ÷ 3/4] = 15/2 - [9/4 x 4/3]
= (15/2 - 3)
= 9 / 2 = 4¹/₂