急!------簡單的數學問題 20點!!!!

梨的數量 = A
橙的數量 = B
小孩人數 = P

梨的數量等於橙的數量的3倍
A = 3B ----------(1)

梨的數量亦等於每個小孩分到8個梨, 並會剩下21個梨
A = 8P + 21 ----(2)

橙的數量等於每個小孩分到5個橙
B = 5P -----------(3)

將A = 3B, B = 5P 代入 (2)
3B = 8P + 21
3(5P) = 8P + 21
15P = 8P + 21
P = 3

所以橙的數量是將P = 3 代入 (3)
B = 5(3)
B = 15

所以梨的數量是將B = 15 代入 (1)
A = 3 (15)
A = 45

總結:
梨總數量是45個 (3小孩共分到 3 x 8 = 24個, 剩餘 21個)

橙總數量是15個 (3小孩共分到 3 x 5 = 15個, 剩餘 0 個)

小孩人數共3個

Let num of kids = x
num of pears = y
num of oranges = z

梨的數量是橙的數量的3倍:
1. y = 3z

每個小孩分到5個橙會剩下0個橙:
2. z = 5x

每個小孩分到8個梨剩下21個梨:
3. y = 8x + 21

From 1 and 2 we get:
4. y = 15x

From 3 and 4 we get:
15x = 8x + 21
7x = 21
x = 3

therefore z = 5 X 3 = 15
y = 3 X 15 = 45

小孩的人數: 15
橙的數量: 45

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