Let the cost of the Mathematics book be x.
The cost of the Science book is x + 0.70.
The cost of the English book is x - 0.85.
The average cost of the three books is (x + x + 0.70 + x - 0.85)/3 = $9.80.
Combining like terms, we get (3x - 0.15)/3 = $9.80.
Multiplying both sides of the equation by 3 gives us 3x - 0.15 = $29.40.
Adding 0.15 to both sides gives us 3x = $29.55.
Dividing both sides by 3 gives us x = $9.85.
So, the cost of the Mathematics book is $9.85.
The cost of the Science book is $9.85 + $0.70 = $10.55.
The cost of the English book is $9.85 - $0.85 = $9.00.
Therefore, the total cost of the cheapest book is $9.00 and the most expensive book is $10.55.
Edmund bought 3 assessment books. The average cost of the 3 books was $9.80. The Science book cost $0.70 more than the Mathematics book.
The English book cost $0.85 less than the Mathematics book.
Find the total cost of the cheapest book and the most expensive book
1 answer