推 banjmin:畫圖阿 x=23 10/28 09:09
→ banjmin:沒玩的x人 有玩的60-x人 10/28 09:10
→ banjmin:60-x-25就是只玩一種一次的每人10元 10/28 09:12
→ banjmin:玩三種的18人 每人30元 10/28 09:12
→ banjmin:玩兩種的(25-18)人 每人20元 10/28 09:13
→ banjmin:全部收800元 一條式子 一個變數 解x 10/28 09:14
Sixty students, each with $30 dollars, visited an arcade that has
the following three games:Super Mario, age of Empires, and Red Alert.
Eighteen of the students played each of the three games, and 25 of them
played at least two of them. No student played any other game at the
arcade, nor did any student play a given game more than once. Each game
costs $10 dollars to play, and the total proceeds from the students visit
$800 dollars. How many of these students perferred to watch and played
none of the games?
這題不知道怎麼解，求救!!
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