If the natural numbers a and b are added to the numerator and denominator of the fraction (28/43), the result is (7/12), then what is the minimum value of a+b?
如果在分数(28/43)的分子分母上分别加上自然数a、b，所得结果是(7/12)，那么a+b的最小值等于多少．
<gadget id="calculator">0 + 5</gadget>
<output>5</output>

<result>5</result>