докажите что a+2b=3c и b+2c3a ,то с+2a=3b

a + 2b = 3c b + 2c = 3a •••••••••••••a = 3c - 2b b + 2c = 3( 3c - 2b ) b + 2c = 9c - 6b 7b = 7c b = c a = 3c - 2c = c a = b = c ••••••••••c + 2a = 3b b + 2b = 3b 3b = 3b