The 1995 U.S. Federal tax rate for married couples was as follows: 10 percent on an adjusted gross income (AGI) between $0 and $32,450; 20 percent on the excess over $32,450 on an AGI between $32,450 and $78,400; and 30 percent on the excess over $78,400 on an AGI between $78,400 and $162,770. (a) Determine the tax function and draw its graph. (b) How much taxes would a married couple pay on an AGI of $40,000? (c) What was the couple's AGI if taxes are $6,381.50?