\(câu1:\\ \left(a+b\right)\times c=a\times c+b\times c\\ câu2:\\ x:6,2=52,2+12,4\times0,1\\ \Rightarrow x:6,2=52,2+1,24\\ \Rightarrow x:6,2=53,44\\ \Rightarrow x=53,44\times6,2\\ \Rightarrow x=331,328\\ câu3:\\ a,7,69\times50=384,5\\ b,12,6\times800=10080\\ câu4:\\ a,1,4\times10=14\\ b,2,1\times100=210\\ c,7,2\times1000=7200\)