Answer:
• let the number be x
• Mathematical interpretation and manipulation of the above statement:
[tex] \hookrightarrow \: { \tt{13 - 3x = 5 + x}}[/tex]
• solve and simplify:
[tex]{ \tt{x + 3x = 13 - 5}} \\ \\ { \tt{4x = 8}} \\ \\ \dashrightarrow \: { \boxed{ \rm{ \: x = 2 \: }}}[/tex]
Answer: The number is 2
