Đáp án:
Bạn tham khảo nhé!
Giải thích các bước giải:
$2a=3b\Rightarrow \dfrac a3=\dfrac b2\\5a=7c\Rightarrow \dfrac a7=\dfrac c5\\\Rightarrow\dfrac a{21}=\dfrac b{14}=\dfrac c{15}\\\Rightarrow\dfrac{3a}{63}=\dfrac{7b}{98}=\dfrac{5c}{75}=\dfrac{3a-7b+5c}{63-98+75}=\dfrac{30}{40}=\dfrac34\\\Rightarrow\left\{\begin{matrix}\dfrac a{21}=\dfrac34\Rightarrow a=\dfrac{63}{4}\\\dfrac b{14}=\dfrac34\Rightarrow b=\dfrac{21}{2}\\\dfrac c{15}=\dfrac34\Rightarrow c=\dfrac{45}4\end{matrix}\right.$
