The difference between the present ages of Praveen and Javed is 4 years. The ratio of their ages after 5 years will be 9: 8. What is Praveen's age at present?

Let's solve this step by step:

Step 1: Let's assume the present age of Praveen is P and the present age of Javed is J. According to the problem, the difference between their ages is 4 years. So, we can write this as:

P - J = 4 ---- (Equation 1)

Step 2: It is also given that the ratio of their ages after 5 years will be 9:8. So, we can write this as:

(P + 5) / (J + 5) = 9/8 ---- (Equation 2)

Step 3: Now, we have two equations and two variables. We can solve these equations simultaneously to find the values of P and J.

Let's multiply Equation 2 by 8 and 9 to get rid of the denominator:

8*(P + 5) = 9*(J + 5)

This simplifies to:

8P + 40 = 9J + 45

Rearranging terms, we get:

8P - 9J = 5 ---- (Equation 3)

Step 4: Now, we have two new equations (Equation 1 and Equation 3). Let's multiply Equation 1 by 8 and Equation 3 by 1 and then subtract Equation 3 from Equation 1:

8P - 8J = 32 8P - 9J = 5

Subtracting these, we get:

J = 27

Step 5: Substituting J = 27 in Equation 1, we get:

P - 27 = 4 P = 31

So, Praveen's present age is 31 years.