The perimeter of a rectangle is 34 units and its width is 6.5 units

Since you technically didn't ask for anything to be solved for, this problem is now solved. Since these types of problems are normally solving for legnth if width is given and vice versa, I will solve for legnth.

perimiter=legnth+legnth+width+width or
p=l+l+w+w
p=2l+2w
subsitute w=6.5 and p=34
34=2l+2(6.5)
34=2l+13
subtract 13 from both sides
21=2l
divide by 2
10.5=l

legnth=10.5 units

Multiply 9 and 67. then multiply 3 with 67. lastly the answer that you got for 9x67 is to be subtracted by the answer you got for 3x67