Answer:
63÷4=$15.75(each sibling gave which made it up to $63)
63-40=$23(amount added together-amount paid)
$23÷4=$5.75(each sibling got back)
63-5.75x
if each contributed $18:
18×4=$72(each contribute 18 dollars so multiply by 4 because 4 siblings)
72-40=32(minus 40 from amount they contributed)
32÷4=$8(divide by 4 to see what each sibling got)
Each sibling got back $8