數學題.快d教我//

Let x degree Celcius be the temperature on Monday.

Then x ( 1- 20%) = x - 6


　　　　　 0.8 x = x - 6

　　　　　　　x = 30

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Let the average temperature on Monday be y.

the average temperature on Tuesday: y-6℃
and also is 20% lower than that on Monday. [y(1-20%)]

So, the equation is :

y-6=y(1-20%)

y-6=0.8y

y=30

2007-11-30 11:49:37 補充：
Tuesday: 24℃Monday: 30℃

Assume x is the average temperature on Monday

x(1-20%)=x-6
0.8x=x-6
0.2x=6
x=30

so, the average temperature on Monday is 30, Tuesday is 24.

Let T = temperature on Monday

T(20%) = 6
T = 6/(20%)
= 30 degree

Temperature on Monday = 30 degree