Answer: n/2-3=13;n=32
Step-by-step explanation: the equation and solution correctly represents this sentence is n/2-3=13;n=32, 
first we have to keep in mind the beginning of the exercise which is (three less) then we know that the 3 has a sign of subtraction(-3), when we meet this, we can know that this exercise has only two possible good answer.
Only the equations which have a (-3) inside will be good,the rest of equation has a 3 with a sum sign
N/2+3=13;n=5 ,
 n/2+3=13;=20
then we can omit the past equations, and this let us this equations as possible.
 n/2-3=13;n=32
 n/2-3=13;n=8 
after this we only need resolve the equation to get a correct result, only the equation with a correct result will be the correct answer, 
then we proceed to clear n from each equation.
for this equation the result must be equal to 8 if we clear n.
 n/2-3=13;n=8 
 n/2-3=13
we pass the three to the other side with sum sign
 n/2=13 + 3
we resolve the sum
 n/2=16
after we pass the 2 multiplying to the other side
 n = 16 × 2
we resolve the product of the multiplication
n = 32
but this answer said the result must be equal to 8
n=8 ≠ n = 32
as this result is different, we can conclude that this is a bad answer,
the we get only one possibility 
this equation
 n/2-3=13;n=32
for this equation the result must be equal to 32 if we clear n.
 n/2-3=13;n=8 
 n/2-3=13
we pass the three to the other side with sum sign
 n/2=13 + 3
we resolve the sum
 n/2=16
after we pass the 2 multiplying to the other side
 n = 16 × 2
we resolve the product of the multiplication
n = 32