[問題]gwd 6-14

[游客]

Q14:
If the average (arithmetic mean) of x, y, and 20 is 10 greater than the average of x, y, 20, and 30, what is the average of x and y?

A. 40
B. 45
C. 60
D. 75
E. 95


我怎麼覺得這題題目怪怪的阿???
答案給E

[marco]

(x+y+20)/3=10+((x+y+20+30)/4)
4x+4y+80=120+3x+3y+150
x+y=190
故 the average of x and y=190/2=95........answer(E)
懂了嗎??有問題再提出來ㄛ~~

[游客]

奇怪,最近是怎樣....
頭腦非常的不清楚
謝謝,macro