Question

Three less than "x" is equal to 13

Answer 1

X - 3 = 13 

x = 16 

16 -3 = 13

Answer 2

<-1-2-3-4-5-6-7-8--10-11-12-13-14-15-16-17-18-19-20->
                                             ^-----------^
Y - 3 = 13
16 - 3 = 13
check your work by adding 3 + 13 wich equals 16.
 X = 16