Well, if the original recipe calls for 10 diced strawberries, and he wants to use 30, thats 3x the original recipe, so he would need to use 4x3 bananas, or 12 bananas,and 3x3 apples, or 9 apples, and 6x3 pears, or 18 pears, so your answer would be;
Ed needs 12 diced bananas, 9 diced apples, 18 diced pears, and 30 diced strawberries.
I hope this helps you! Sorry if I got it wrong, I'm not too good with these.