Assume that C is the original cost of the typewriter
then, they got 15% as markup plan.
now,c+(c*.15)=129.95$
c+.15c=129.95
1.15c=129.95
c=113$
the actual cost of the typewriter is , 113$
given cost of the typewriter = $129.95
markup offer = 15%
15% markup on 129.95 = 15 x 129.95 / 100
=19.5
Now original cost = 129.95 - 19.5 = $ 110.5