what can i do ???

Q1- Sir unme se kuch readymade baked items jaise ki cake, pastries, pizza base, puff main other state se mangata hu. Unke bill me mujhe 18% igst dena padta hai. Maan lijiye ek pastry ka rate pehle 40/- per piece tha aur ham use 50/- per piece me sell karte the ab 1 july se same pastry mujhe 47.20/- pad raha hai. To kya main apna margin badha ke customer se le sakta hu?