3a = 2b => a/2 = b/3 => a/10 = b/15 (1)
7b = 5c => b/5 = c/7 => b/15 = c/21 (2)
từ (1) và (2) => a/10 = b/15 = c/21
áp dụng t/c DTSBN ta có:
\(\frac{a}{10}=\frac{b}{15}=\frac{c}{21}=\frac{a+b+c}{10+15+21}=\frac{92}{46}=2\)
=> \(\frac{a}{10}=2=>a=20\)
=> \(\frac{b}{15}=2=>b=30\)
=> \(\frac{c}{21}=2=>c=42\)
vậy a = 20
b = 30
c = 42
Ta có:
3a=2b\(\Rightarrow\frac{a}{2}=\frac{b}{3}\)và 7b=5c =>\(\frac{b}{5}=\frac{c}{7}\)
Ta thấy:
\(\frac{a}{10}=\frac{b}{15}\)và\(\frac{b}{15}=\frac{c}{21}\)=> \(\frac{a}{10}=\frac{b}{15}=\frac{c}{21}\)=>\(\frac{a+b+c}{10+15+21}=\frac{92}{46}=2\)=>a= 2 *10+20
b= 2*15=30
c=2*21=42
