Answer:
1/2x - 8
Step-by-step explanation:
Let
x = number of pledges she collected last year
The number of pledges that Melissa collected for this year's charity walk is 8 less than half the number of pledges she collected last year.
Number of pledges she collected this year = 1/2x - 8
The expression which represents the number of pledges she collected this year = 1/2x - 8
