order of operations says parenthesises / exponents first, then multiply/divide from left to right ( whatever one comes first from left to right if its all multiplication/division)
then add/subtract from left to right (whatever one comes first from left to right)
your problem 18/3- 4x2+5
first you have to multiply/divide from left to right
18/3= 6 and 4x2 is 8 now rewrite it
6-8+5 now that their all add/subtract just go from left to right
6-8= -2 +5 = 3
3 is your answer