Without factoring in the cost of depreciation for his car John made $30,000 doing Uber.  When he finally traded in the car he bought for $18,000 he got $6000 back.  What was his profit from driving Uber?
His car depreciated 18000-6000=$<<18000-6000=12000>>12000
So he made a profit of 30000-12000=$<<30000-12000=18000>>18000
#### 18000