A motorbike company sold 66 bikes in a special 3-day sale. Each day the company sold 8 more than the previous day. How many bikes were sold on the third day?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 30
Each day’s sales are 8 more than the day before, so all three days can be written in terms of the first day’s sales, \(x\): \(x\), \(x+8\) and \(x+16\).
The three days together sold 66 bikes: \(x+(x+8)+(x+16)=66\)
\(3x+24=66\)
\(x=14\)
Bikes sold on the third day \(=14+16=\) 30
Shortcut: When numbers go up by the same step, the middle one is their average.
Second day \(=66\div3=22\)
Third day \(=22+8=30\)