3x+1+½x+3=18, (this is what I think the question is and we have to find x)
3½x+4=18, (collect like terms together)
7x/2=14, (write 3½ as an improper fraction and subtract 4 from each side)
x/2=2, (divide both sides by 7)
x=4. (multiply both sides by 2)