(10.3 * 10.3 * 10.3 + 1)/(10.3 * 10.3 - 10.3 + 1) is :

a^3 + b^3 = (a+ b) * (a^2 + b^2 - ab)

[ (10.3)^3 + (1)^3 ] / [(10.3)^2  + (1)^2 - (1 * 10.3)]

 => a + b = 10.3 + 1 = 11.3