左辺を変形していくといいですよ。
10×x/100+11×(100-x)/100=10.8
10x/100+11(100-x)/100=10.8
10x+11(100-x)=1080
10x+1100-11x=1080
10x-11x=1080-1100
-x=-20
x=20
Answers
Were you able to resolve your confusion?
Users viewing this question
are also looking at these questions 😉
ありがとうございます！