Let x be the cost of one book 12 books =54.84 1 book =x Cross multiplying the equations ⇒12×x=1×54.84 Divide both sides by 12 ⇒x=54.84∕12 ⇒x=4.57 Thus To simplify the fraction, change the decimal number to a form which has 10 raised to the power by moving the decimal position to the right until you get a whole number. Multiply that whole number by 10 raised to the power negative of the number of times you moved to the right Thus 58.84=5884×10−2 NOTE:The power is negative if you moved to the right and positive if you move to the left ⇒x=54.84∕12=5884×10−2∕12 Using long division to simplify, ⇒5884×10−2∕12=457×10−2 Now change 457×10−2 back to decimal. 457 is the same as 457.0 , thus every whole number has point zero decimal Since the 10 is raised to the power -2 , we move the decimal point to the left 2 times, which gives us 4.57 Alternatively, you can multiply each of the possible answers by 12 and the one that gives you the total cost of the 12 books (GH₵ 54.84) is the answer.