數學題....我只係要式(10)!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

小明测驗有30題..答對有3分 答錯扣一分

小明做哂全部 小明最小有60分

咁佢最多答錯幾多題?? 答案 : 7題

設小明最多答錯了 x 題..

我只係要條式~~~唔該...幫幫手~~

可以:

(30x3-60)÷(3+1)
=30÷4
=7 1/2
~7

設小明最多答錯了x題。
3(30-x)+x(-1)>60
90-3x-x>60
90-4x>60
90>60+4x
90-60>4x
30>4x
7.5>x
x<7.5
∴小明最多答錯了7題。

The answer is:
60-7x

Number of questions that is correct = 30 - x.
Marks received = 3(30 - x).
Marks deducted due to wrong answers = -x.
so 3(30 - x) - x > 60.
90 - 3x - x > 60
30 > 4x
7.5 > x
so greatest value of x = 7.

設小明最多答錯了 x 題

(30-x) *3 + x(-1) >60

Number of questions that is correct = 30 - x.
Marks received = 3(30 - x).
Marks deducted due to wrong answers = -x.
so 3(30 - x) - x > 60.
90 - 3x - x > 60
30 > 4x
7.5 > x
so greatest value of x = 7.