how to do this question please explain it to me as fast as possible and please do this question properly

(i) area of hall = 1800 cm * 1350 m = 2430000 cm²
area of square tiles = 25 cm * 25 cm = 625 cm²
no. of tiles required = 3888
cost = 3888 * rs6 = 23328
(ii) length of hall = 18 m - 1.5 m - 1.5 m = 15 m = 1500 cm
     the breadth of hall  = 13.5 - 1.5 - 1.5 = 10.5 m = 1050 cm
     area of hall = 1500 cm * 1050 cm = 1575000 cm²
     area of tiles = 625 cm²
     no. of tiles = 2520
     cost = 2520 * 6 =  Rs15120
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