Please solve

Question

A car lot had `138 cars. All of the Cars were either foreign or convertibles. Some were both. There were 82 foreign cars and 65 convertibles. How many cars were foreign convertibles?

 

Answer 1

(82 - x) + (65 - x) + x = 138

147 - x = 138

x = 9 cars are both

 

Or think of it this way

82 + 65 = 147 cars if there were no foreign convertibles. But there are only 138 cars so 147 - 138  = 9 cars must be both.