<prompt> Translate the following text to SwahiliBecause a large proportion of street costs are fixed,27 the unit per piece street cost initially declines rapidly as volume increases and continues to decline at a decreasing rate.  <response>: Kwa sababu sehemu kubwa ya gharama za barabara ni fasta, gharama ya barabara ya kitengo kwa kipande mwanzoni hupungua haraka kama kiasi huongezeka na inaendelea kupungua kwa kiwango cha kupungua. 