0.25k + 1.5 - k - 3.5
You must combine like terms. Like terms are the numbers with the same variable (letter) attached (in this case the numbers with the letter k are like terms)
(0.25k + (-k) )+ 1.5 - 3.5 <<<Remember that a variable with no number in front of it still has and invisible 1
(0.25k + (-1k) ) + 1.5 - 3.5
-0.75k + 1.5 - 3.5
Numbers without any variable are also like terms
-0.75k + 1.5 - 3.5
-0.75k -2
Hope this helped!
~Just a girl in love with Shawn Mendes