The current age of B is 35 years, and five years from now, the ratio of the age of A to B will be 3 : 4. If the present age of C is 40% more than the present age of A, then what was the age of C seven years ago?

The correct answer is 28 years.

Step 1: Find the age of B five years from now.
The present age of B is given as 35 years.
Five years from now, the age of B will be:

$\text{Age of B after 5 years}=35+5=40\text{years}$

Step 2: Find the present age of A.
Five years from now, the ratio of the age of A to B will be 3 : 4.
Let the age of A after 5 years be $A_{\text{future}}$.
Using the given ratio:

$\frac{A_{\text{future}}}{40}=\frac{3}{4}$

$A_{\text{future}}=40\times \frac{3}{4}=30\text{years}$

Subtract 5 years to find the present age of A:

$\text{Present age of A}=30-5=25\text{years}$

Step 3: Find the present age of C.
The present age of C is 40% more than the present age of A.
Calculating 40% of 25:

$40\%\text{of}25=\frac{40}{100}\times 25=10\text{years}$

Therefore, the present age of C is:

$\text{Present age of C}=25+10=35\text{years}$

Step 4: Find the age of C seven years ago.
Subtract 7 years from the present age of C:

$\text{Age of C 7 years ago}=35-7=28\text{years}$

Thus, the age of C seven years ago was 28 years.