Hassan predicted that he would sell 178 postcards. He actually sold 142 postcards. What are the values of a and b in the table below? Percent Error

Item
Approximate value
Exact value
Error
Absolute error
Ratio
Percent error
Postcards
178
142
a
b

a = negative 36; b = negative 36
a = negative 36; b = 36
a = 36; b = negative 36
a = 36; b = 36