If the natural numbers a and B are added to the numerator and denominator of 28 / 43 of the fraction, the result is 12 / 7, then what is the minimum value of a + B

If the natural numbers a and B are added to the numerator and denominator of 28 / 43 of the fraction, the result is 12 / 7, then what is the minimum value of a + B

a=56,b=7,
The minimum value of a + B is 63