In ΔABC, ∠B = 70°and ∠C = 60°. The internal bisectors of the two smallest angles of ΔABC meet at O. The angle so formed at O is
If a - b = 3 and a2 + b2 = 25, then the value of ab is
The simple interest on a sum for 5 years is two-fifth of the sum. The rate of interest per annum is
The average of marks of 17 students in an examination was calculated as 71. But it was later found that the mark of one student had been wrongly entered as 65 instead of 56 and another as 24 instead of 50. The correct average is
If a shop keeper marks his goods for a certain amount so as to get 25% gain after allowing a discount of 20%, then his marked price is