In the given figure, PQRS is a square of side 20 cm and SR is extended to point T. If the length of QT is 25 cm, then what is the distance (in cm) between the centres O₁ and O₂ of the two circles?

The ratio of the number of students to the number of girls students in the school of 1638 students is 5: 2. If the number of girl students increases to 60, then what should be the decrease in the number of students to keep the new ratio of students to girls 4: 3?

The ratio of number of men and women in a factory of 720 workers is 7 : 5. How many more women should be joined to make the ratio 1 : 1?

Ankur borrowed sum money from Megha at 8 % P.a simple interest and twice the amount from Harshita at 9 % P.a simple interest. He then added some more money of his own and lent the entire amount to Shalini at 10 % p.a simple interest. At the end of the year Ankur gained 14,000. If Ankur lend ₹ 40,000 to Shalini, then how much did Ankur borrow from Megha ? 

In a 1500 m race, Chaitali beats Vrunali by 100 m and in 1200 m race, Vrunali beats Krutika by 75 m. If Chaitali and Krutika are compared, then for how much m Chaitali will beat Krutika in 900 m race?