Solutions 
We know that five potatoes together have a mass of one kilogram and eight pears together have a mass of 1200 grams. 
5 potatoes = one kilogram 
eight pears = 1200 grams 
To solve the problem we have to convert 1 kilogram into grams. 
1 kilogram = 1000 grams 
Now we have 
5 potatoes = 1000 grams 
eight pears = 1200 grams 
The next step is to use division:
1000 ÷ 5 = 200 -> 1 potato weighs 200 grams.
1200 ÷ 8 = 150 -> 1 pear weighs 150 grams
Therefore a potato has a greater mass than a pear.