Four years ago,the father's age was three times the age of his son. The total of the ages of the father and the son after four years will be $64$ years. What is the father's age at present (in years)?

If $1,000$ copies of a book of $25$ sheets require $50$ reams of paper,how much paper is required for $5,000$ copies of a book of $32$ sheets?

Hitesh is $40$ years old and Ronnie is $60$ years old. How many years ago was the ratio of their ages $3:5$?

Three numbers are in the ratio $2:5:7$. The sum of the smallest and largest numbers equals the sum of the second number and $16$. What is the smallest number?

The ratio of the present age of Manoj to that of Wasim is $3:11$. Wasim is $12 \text{ yr}$ younger than Rehana. Rehana's age after $7 \text{ yr}$ will be $85 \text{ yr}$. What is the present age (in $\text{yr}$) of Manoj's father,who is $25 \text{ yr}$ older than Manoj?

What number should be added to or subtracted from each term of the ratio $17: 24,$ so that it becomes equal to $1: 2?$