The given weight of Joshua's math textbook = 4.21 ounce
The given weight of Joshua's social studies textbook = 3.99 ounce
Hence, the difference in weight between the both the textbooks is- subtract the weight of social studies textbook from math textbook, which is:
4.21 - 3.99 = 0.22 ounce
Hence the difference in weights is 0.22 ounce.
