A = \(\dfrac{1}{2}\): 5 + \(\dfrac{1}{4}\): 0,25 + \(\dfrac{1}{8}\): 0,125
A = \(\dfrac{1}{2}\) \(\times\) \(\dfrac{1}{5}\) + \(\dfrac{1}{4}\) \(\times\) 4 + \(\dfrac{1}{8}\) \(\times\) 8
A = \(\dfrac{1}{10}\) + 1 + 1
A = 0,1 + 2
A = 2,1
nhầm laf 1/2 : 5 + 1/4 : 0,25 + 1/8 : 0,125