Đáp án:
Ta có:
7,175=5.12+6.5+7.3+8.n+9.12+10.2/12+5+3+n+12+2
7,175=60+30+21+8n+108+20/n+34
7,175=239+8n/n+34
=>7,175(n+34)=239+8n
=>7,175.n+7,175.34=239+8n
=>7,175.n+243,95=239+8n
=>7,175-8n=-243,95+239
=>(7,175-8).n=-4,95
=>-0,825n=-4,95
=>n=5,675
=>n sấp xỉ 5,7