a. The combined taxes is represented by y and your total income is represented by x
Now, if the salary is greater than 102,000 social security is a fixed amount that is equal = 102,000*0.062 = 6,324. This is because you pay social security tax only on your first 102,000
The piece wise function is as follows:
y = 0.062*x +0.0145*x if x <=102,000
y = 6,324 + 0.0145*x if x>102,000
b. John's social security = 102,000*0.062 = $6,324 (Since you pay social security tax only on your first 102,000)
c. John's medicare tax = 0.0145*102,000 = $1,479