The 1990 U.S. Federal Tax rate of married couple was as follows: 15% on an AGI between $0 and $ 32,450: $4867.60 plus 28% on the excess over $ 32,450 on an $32450 AGI between $32450 and $ 78,400 and $17733.50 plus 33% on the excess over $78400 on an AGI between $78400 and $162770. i. Determine the tax function and draw its graph. ii. How much taxes would a married couple pay on an AGI of $15000 ? iii. How much taxes would a married couple pay on an AGI of $35000? iv. How much taxes would a married couple pay on an AGI of $85000? v. What was the couple's AGI if taxes are $8381.50 ?