Question

Bo is buying a board game which usually costs B dollars. The game is on sale, and the price has been reduced by 18% There are different ways of thinking about how to calculate Bo's final bill. Match the expressions to their meanings.

Answer 1

0.18B is neither of these.  
B-0.18 is neither of these.
0.82B is calculate the percent he pays, then convert it to a decimal and multiply to get the final price.
B-0.18B is calculate the dollar amount of discount and subtract it from the original.

Explanation
0.18B will tell you what 18% of the price, B, is, but does not tell you anything else.

B-0.18 will take the price, B, and subtract $0.18 from it.  It does not find a percentage.

0.82B is the same as taking 82% of B.  We would do this because 100% of the price - 18% discount = 82%; 82% = 82/100 = 0.82.

B-0.18B takes the price, B, and subtracts 18% of B.  18%=18/100 = 0.18, so 0.18B is 18% of B.