Call the weight of the bag of apples as x (x = 6 2/7)
Since the crate of bananas is 4 times as heavy as the apples -> the crate of bananas = 4x
So, to find the weight difference, we minus those : 4x - x = 3x
Now we convert this : 3x = 3 x 6 2/7 = 132/7
Convert to :
Mixed : 18 6/7
Decimals (3 d.p) : 18.857...