Answer: Lena eats 1/4 of the whole bar
Step-by-step explanation:
Half of the bar is 50. A full bar would be 100%. If Phillip has half, amd Lena eats half of that half, she eats 0.25 out of 0.5. 0.5 is half of the whole bar, so 0.5×0.5 is 1, and if lena ate 0.25 of 1, that is 1/4.