Question

write an algebraic expression representing three less than half a number

Answer 1

If x is the number you start with, three less than half of that is
x/2 -3

Answer 2

let n = number
half the number, so n/2
three less than, so - 3
putting them together, three less than half a number is:
n/2 - 3

*i just reposted my reply :)