Average score of Rahul, Manish and Suresh is 63. Rahul's score is 15 less than Ajay and 10 more than the average sores of Rahul, Manish and Suresh, what is the sum of Manish's and Suresh's scores?

$35$ is the average marks obtained by $120$ students. The average marks of successful candidates was $39$, and that of unsuccessful candidates was $15$. What is the number of successful candidates in that examination?

Average of three numbers $\mathrm{B}, \mathrm{C}$ and $\mathrm{D}$ is $1$ more than the average of $\mathrm{A}, \mathrm{B}$ and $\mathrm{C}$. Average of $\mathrm{A}$ and $\mathrm{D}$ is $19.5$.

Quantity $1$: Find $\mathrm{A}$.

Quantity $2$: $21$.