5 pens and 1 exercise books cost KSh 180, while 7 pens and 4 exercise books cost KSh 356. Find the cost of one exercise book.

Answer and explanation

Correct answer: B. KSh 40

  1. Step 1: Let a pen cost p and a book cost b: 5p + 1b = 180 and 7p + 4b = 356. Step 2. Multiply the equations so that the p terms match, then subtract to eliminate p. Step 3. This gives b = 40, and substituting back gives p = 28. Answer: KSh 40. Why not the others: KSh 28: That is the price of one pen. KSh 58.67: That subtracts the two bills without first making the pen terms equal. KSh 30: That divides the first bill by the total number of items, as if pens and books cost the same.

Practise more Simultaneous equations.

Free questions with an explanation for every one, and full timed Kenya KCSE mock tests.

All Simultaneous equations questionsTake a mock test

More Simultaneous equations questions