Answer:
A. $70,000
Step-by-step explanation:
From the information given, we discover that
Gross profit from sporting goods business = $100,000 
Subtract: other Expenses = 11500 
Subtract: Building depreciation expenses (10000 × 55%) = 5500 
Subtract: Mortgage Interest (10000 × 55%) = 5500 
Subtract: Depreciation on vehicle used for business = 3000 
Less: Utilities for Ground Floor = 4500 
Net Self employment Income = $70,000 
Note that 55% is used for ground floor, it is calculated as 100 - 45% used by tenant, therefore, for business purpose 55% will be taken.