The sum of 3% of a number and 2% of the other number is equal to 3/4 of the sum of 3% of the first number and 5% of the second number. The ratio of the 1st number to 2nd numbers is: 

(3% of the first number + 2% of the second number) = $$\frac{3}{4}$$​ ( 3% of the first number + 5% of the second number)

Let the two numbers are x and y respectively:

​$$\frac{3}{100}\times x +\frac{2}{100}\times y =\frac{3}{4}(\frac{3}{100}\times x+\frac{5}{100}\times y)\\ \ \\ \frac{3}{100} x +\frac{2}{100}y =\frac{9}{400}x+\frac{15}{400}\\ \ \\ 3x+2y=\frac{9}{4}x+\frac{15}{4}y\\ \ \\ 12x+8y=9x+15y\\ \ \\ 3x=7y\\ \ \\ \frac{x}{y}=\frac{7}{3}\\ \ \\\text{ Required ratio} = 7:3$$​​

Thus, correct option is (c).