问一道钩钩题，大家帮忙看一下

kidyrain

l
                一面墙还是什么的面积是S平方米，M和N 两人都以X平方米每小时的速度在上面画画，问M干了多长时间

 

  A.N比M多少了a个小时

  B.N从早8点做到早11点

 （S，X，a具体数字已知）

这道题为什么会是d呢

条件一是怎么知道m干了多长时间？

 

切尔西

(S-X*A)/2X

frankmfg

Statement 1.
I would approach this question like this. We are given that S, X, A are actual numbers.
The total amount of work they did together is S. Let's say M did y hours of work. So, the equation would be: Xy+X(y+A)=S
Plug in S, X, and A into the equation and we can get y.

Statement 2 is pretty much a no-brainer.