Two question's dealing with average or effective markup!

Hey I would really appreciate if some one could show me the calculations for these questions as my text is lacking examples. I have been given the answers but need to show the work and personally I need to understand how to do this for my exam!

1.) A grocery store paid $18.00 for 120 pounds of grapes and it wants a 35% average or effective markup based on Cost. It expects to move 5% over to the "reduced" table and sell them for $.06 a pound. Assuming no waste,

(A) at what amount must they price the remainder?

**Calculations needed**

Answer = $.21 cents

(B) What percentage markup does this represent?

**Calculations needed**

Answer = 28.57% base on sales price or 40 % base on cost.

2.)You buy three hundred pairs of sunglasses at the beginning of the summer. You estimate that ten percent of them will have to be put on your "bargain table" at the end of the season on which everything is prices at $1.00. 30% of the bargain table items will be damaged or broken and will have to be thrown away. If the Glasses cost you $2.00 per pair and you want to have an average mark up of 38% based on selling price, At what price must you start selling the sunglasses?

**Calculations needed**

Answer = $3.51 A Pair.

If you could show me how to do this i would be very grateful cheers!