If each of the odd digits in the number 6234518 is changed to the next even digit and the even digits are kept unchanged, how many digits will appear only once in the new number?

Rachita enters a shop to buy ice-creams, cookies and pastries. She has to buy atleast $9$ units of each. She buys more cookies than ice-creams and more pastries than cookies. She picks up a total of $32$ items. How many cookies does she buy?

The fare of a bus is Rs. $X$ for the first five km and Rs.$13$ per km thereafter. If a passenger pays Rs. $2402$ for a journey of $187$ km, what is the value of $X$?

Akash scored $73$ marks in Subject A. He scored $56\%$ marks in Subject B and X marks in Subject C. Maximum marks in each subject were $150$. The overall percentage marks obtained by Akash in all the three subjects together were $54\%$. How many marks did he score in Subject C?

The area of a square is $1444 {\mathrm{m}}^2$. The breadth of a rectangle is $\frac{1}{4}\mathrm{th}$ the side of the square and the length of the rectangle is thrice the breadth. What is the difference between the area of the square and the area of the rectangle?