Answer: 17.56%
Explanation:
Given that,
Leonardo taxable income = $90,000
Tulsa bonds = $8,750
Theresa taxable income = $50,000
Computation of Leonardo's Tax:
According to the tax rate schedule,
Total Tax = Tax + 24% of taxable income over $82,500
                 = $14,089.50 + 24% × $7,500
                 = $14,089.50 + $1,800
                 = $15,889.5
Computation of Theresa's Tax:
According to the tax rate schedule,
Total Tax = Tax + 22% of taxable income over $38,700
                 = $4453.50 + 22% × $11,300
                 = $4453.50 + $2,486
                 = $6939.5
Total tax on Leonardo's income and Theresa's income: 
= $15,889.5 + $6939.5
= $22,829
 Effective tax rate = 
                               = 
                               = 17.56%