Đáp án+Giải thích các bước giải:
Từ đề bài, ta có:
`A/B=`$\dfrac{\dfrac{34}{7.13} + \dfrac{51}{13.22}+ \dfrac{85}{22.37} + \dfrac{68}{37.49}}{\dfrac{39}{7.16} + \dfrac{65}{16.31} + \dfrac{52}{31.43} + \dfrac{26}{43.49}}$
`A/B=`$\dfrac{\dfrac{17}{3} . (\dfrac{6}{7.13} + \dfrac{9}{13.22} + \dfrac{15}{22.37} + \dfrac{12}{37.49})}{\dfrac{13}{3} . (\dfrac{9}{7.16} + \dfrac{15}{16.31} + \dfrac{12}{31.43} + \dfrac{6}{43.49}}$
`A/B=` $\dfrac{\dfrac{17}{3}.(\dfrac{1}{7} - \dfrac{1}{13} + \dfrac{1}{13} - \dfrac{1}{22} + \dfrac{1}{22} - \dfrac{1}{37} + \dfrac{1}{37} - \dfrac{1}{49})}{\dfrac{13}{3}.(\dfrac{1}{7} - \dfrac{1}{16} + \dfrac{1}{16} - \dfrac{1}{31} + \dfrac{1}{31} - \dfrac{1}{43} + \dfrac{1}{43} - \dfrac{1}{49})}$
`A/B=` $\dfrac{\dfrac{17}{3}.(\dfrac{1}{7} - \dfrac{1}{49}}{\dfrac{13}{3}.(\dfrac{1}{7} - \dfrac{1}{49})}$
`A/B=` $\dfrac{\dfrac{17}{3}}{\dfrac{13}{3}}$
`A/B=` $\dfrac{17}{3}$ : $\dfrac{13}{3}$
`A/B=` $\dfrac{17}{13}$
