(a) Given that a certain population decreased by 48,000 people and that we should write a signed number to represent this population change.
From the question, we are told that the population decreased by 48,000 people.
Let the initial population be x
So, if the population decreased by 48,000 people, that means there is a reduction from the initial population.
To represent the reduction in growth, we use the subtraction operator.
Therefore, a signed number representing the population change is: x - 48,000, which can also be seen as -48,000
(b) Given that Rachel received 100 dollars. We are to write a signe number to represent this change.
To write a signed number of Rachel receiving 100 dollars is, that means Rachel finance is been increased by 100 dollars.
Therefore, the signed number can be written as +100 dollars.