Part A)
Multiply the amount he earned by 8.5%
8.5% written as a decimal is 0.085.
75,000 x 0.085 = $6,375
Part B)
Subtract the amount of tax from his earnings:
75,000 - 6,375 = $68,625
The number u looking for is 28
6,080,010 hope this helps you
Use the concept of Lagrange multipliers.