You need to find the lowest common factor of the 2 denominators from the fractions. So, 8x3 = 24 and 12 x 2 = 24. 24 is their LCF. Then you times 3 by 3 which is 9 and 5 by 2 which is 10. Apple pie = 9/24 and Strawberry pie = 10/24. So Cole ate more. Unfortunately I don't know how to write the mathematical expression for this. However I hope this helps :)
