Contract costing

Please help me in this question as i am lacking in it . please see to it  and try to give solution of it .

A contract for construction of building is governed by escalation clause in respect of prices of steel,

cement, and stone aggregate.The prices ruling on the date of tender for building and actual prices paid by the contractor  were  as follows:

                                                       On date of tender            actual      

 Steel per ton                              610                                          675

Cement p                                 100                                          105

Stone aggregate per 100 cft  40                                             38

3,00,000 c.ft. of reinforced  cement concrete was laid in the building.If 100lbs of steel , 2400lbs of cement  and 90c.ft. of stone are net quantity required to cast 100c.ft. of RCC  and wastage are 5,3 and 10 % respectively. Calculate the difference in selling price according to estimate clause (1 ton = 2,240 lbs).Assume the wastage % based on net quantity of material.