 
<translate> Kowane wata na biyu Nina tana yin nisan sau biyu, wanda ke nufin 400 * 2 = kilomita 800. Shekaru biyu watanni 24 ne, don haka rabin wannan lokacin ya zama 24 * 0.5 = watanni 12. Saboda haka a cikin watanni 12 Nina ya yi 400 * 12 = 4800 kilomita. Kuma a cikin sauran watanni 12, ta yi 800 * 12 = 9600 kilomita. Saboda haka a cikin shekaru biyu, Nina zai iya yin 4800 + 9600 = 14400 kilomita. <eng> Every second month Nina does twice the regular distance, which means 400 * 2 = 800 kilometers. Two years is 24 months, so half of this time is 24 * 0.5 = 12 months. So in 12 months Nina does 400 * 12 = 4800 kilometers. And in the other 12 months, she does 800 * 12 = 9600 kilometers. So in two years, Nina would be able to make 4800 + 9600 = 14400 kilometers. 