In a certain code, 327 means 'don't cut tree', 635 means 'plant one tree', 138 means 'tree gives shade' and 4953 means 'we must plant tree'. Which digit represents 'shade'?
X and Y are two alloys which are prepared by mixing zinc and aluminium in the ratio of 1 : 4 and 11 : 8 respectively. If equal quantities of alloys are melted to form a third alloy Z then what is the ratio of zinc and aluminium in alloy Z?
The marked price of a pen is Rs 3000. The shopkeeper gives two successive discounts of 15% and a% to the customer. If the customer pays Rs 2142 for the pen, then what is the value (in percentage) of a?