What is the volume, in cubic feet, of a rectangular room that has length x feet, width y feet, and height z feet?
(1) x=1,200/yz
(2) The area of the ceiling of this roo is 120 square feet and the area of each of two facing walls of this room is 100 square feet.
Explanation of statement (2)
Insufficient. xy=120 and either xz=100 or yz=100. So you have two equations and three unknowns. You can't solve for the values of x, y and z. There is also no way of combining these equations to give you xyz
请问（2）当中的each of the facing walls该怎么理解呢？原来以为是指任意一面墙，现在看解释的意思指有一面墙。恳请哪位NN指点一下each的用法 | 
