Answer:
(a). +11
(b). -35
Step-by-step explanation:
(a). An increase in mathematics is represented by a + sign.
Therefore, if we want to represent a score increase by 11 points, well say that the score changed by +11.
Note that if we didn't use + sign, we would use the following sentence to describe the same change.
Lisa's test score average increased by 11 points.
If on the other hand, we used the + sign, we'd say
Lisa's test score average changed by +11 points.
(b). A decrease in mathematics is represented by a - sign.
Therefore, if we want to describe a loss of $35 from Charmaine's pocket, we'd say the following.
Charmaine's pocket money changed by - 35 dollars.