Convert it to an equation.
"Three times a number"
[tex]\sf 3n[/tex]
"is"
=
"the difference between four and that number"
[tex]\sf 4-n[/tex]
Put it all together:
[tex]\sf 3n=4-n[/tex]
Solve for 'n', add 'n' to both sides:
[tex]\sf 4n=4[/tex]
Divide 4 to both sides:
[tex]\boxed{\sf n=1}[/tex]
