How to do this question? I don't really know how to get the number I highlight in the solution, please help me step by step. Thx

Question 47 (31 minutes) [Chapter 11, 12] The controller of Above All Inc. (AA Inc.) provided you with the following selected information related to the 2011 taxation year ended December 31, 2011. AA Inc. is a Canadian-controlled private corporation. AA Inc. did not have taxable capital excess of $10,000,000 in 2010. Canadian manufacturing and processing profits (correctly computed using the rules in regulation 5200 of the Act) $451,500 Canadian retail business income 50,000 U.S. retail business income (before U.S. tax paid of $15,000) 40,000 Taxable capital gains 4,500 Interest income: Canadian long-term bonds 20,000 Interest on overdue accounts receivable 5,000 Dividend income: From taxable Canadian corporations (AA owns less than 5% of the shares of these corporations) 9,000 From U.S. corporations (before U.S. tax of $1,800) corporations are not fore affiliates) 12,000 Net capital losses from prior years applied in the calculation of taxable income 4,500 Calculations correctly prepared under the Income Tax Act Taxable income Part I tax payable (including additional refundable tax) Foreign business tax credit Foreign non-business tax credit $503,500 90,938 15,000 1,800 Miscellaneous Items Refundable dividend tax on hand as of December 31, 2010 Dividend refund received in respect of the 2010 taxation year Taxable dividends paid during 2011 $20,000 9,000 120,000 Required: Determine, for AA Inc., by clearly presenting all component parts and their calculations, (a) the amount of the small business deduction, and (8 minutes) (b) the amount of the dividend refund for 2011. (23 minutes) Do not re-compute the Part I tax and the other related tax credits. Assume that they have been computed correctly. Solution 47 Small Business Deduction 17% of least of: A) Canadian source ABI ($451,500 + $50,000+ $5,000) B) Taxable income Less: 10/3 NBFTC (10/3 $1,800) 3.77 BFTC (3.77 * $15,000) $506,500 $503,500 (6,000) (56,550) $440,950 $500,000 $ 74,962 C) Business limit Least amount is 17% of $440,950 Dividend Refund Refundable portion of Part I tax Least of: (i) 264% * Aggregate investment income 26%% ($4,500 + $20,000+ $9,000+ $12,000 - $9,000 - $4,500) = Less: NBFTC -94% * FII ($1,800 - 94% $12,000) S 8,533 (680) $ 7,853 $503,500 (ii) Taxable income Less: SBD amount 25/9 NBFTC (25/9 * $1,800) 3.77 BFTC ($15,000) (440,950) (5,000) (56.550) $1,000 26%% of $1,000 S 267 (iii) Part I tax, including ART $90,938 Least amount is: S 267 Part IV tax Portfolio dividends ($9,000 x 33%%) $ 3.000 Refundable dividend tax on hand RDTOH, December 31, 2010 Deduct: Dividend refund for 2010 $20,000 (9.000) $11,000 267 _ 3,000 Add: Refundable portion of Part I tax Part IV tax payable $14,267 Dividend refund Lesser of: Taxable dividends paid in fiscal 2011 ($120,000 > A) RDTOH at December 31, 2011 Lesser is: $40.000 $14,267 $ $14,267