What value should come in place of the question mark (?) in the following question?

52x14+145018=1998÷?

Bhanu takes a total of 6 hrs 50 min in walking a distance and running back to same place where she started. She could walk both ways in 8 hrs 30 min. The time taken by her to run both ways is :

(242699 + 167109) ÷ (9946 –9446) = ?

(45.004% of 1439.97 –15.99% of 2249.97) ÷ 35.98 = ?

874.96 + 94.0091 × 34.98 –1244.98 = ?

Solve 675.9995+(3.9989)2 = ? ÷ 16.9900865

Solve : 8,23,199.98 × 99.92 = ? × 80,000

In a college, the ratio of boys to girls is 29 : 33 respectively. When 142 more boys join the college, this ratio becomes 21 :19. How many more girls should join the college to make the number of boys and girls equal?

A watch dealer sells watches at Rs 600 per watch. However,he is forced to give two successive discounts of 10% and 5% respectively. However, he recovers the sales tax on the net sale price from the customer at 5% of the net price. What price does a customer have to pay him to buy the watch?