✔ 最佳答案
1.
Let n be the smaller integer.
They are two consecutive (連續的) integers.
Then the larger integer = n + 1
Sum of the two numbers = 83 :
n + (n + 1) = 83
2n = 82
n = 41
The two integers are 41 and 42.
*****
2.
Let d m be the total length of the journey.
Then, Distance for uphill = Distance for downhill = 0.5d m
Time = Distance/Speed
Time for uphill + Time for downhill = 4.2 h
(Distance for uphill)/(Speed for uphill) + (Distance for downhill)/(Speed for downhill)= 4.2 h :
(0.5d/4) + (0.5d/3) = 4.2
12[(0.5d/4) + (0.5d/3)] = 12(4.2)
1.5d + 2d = 50.4
d = 14.4
The total length of the journey is 14.4 m.
(It will be more realistic if the unit of length is km instead of m.)
*****
3.
Let t the tens digit.
The unit digit is greater than the tens digit by 3.
Then, the units digit = t + 3
The value of a two-digit number = (10 x tens digit) + units digit
Hence, the original number = 10t + (t + 3)
and the new number obtained by interchanging the two digits = 10(t + 3) + t
Sum of the original number and the new number obtained = 121 :
[10t + (t + 3)] + [10(t + 3) + t] = 121
22t = 88
t = 4
t + 3 = 7
The original number is 47. The new number obtained is 74.
2012-08-14 01:55:06 補充：
2.
Length of uphill part = Length of downhill part
But (Length of uphill part) + (Length of downhill part) = d m
Then, Length of uphill part = Length of downhill part = 0.5d m
