兩條數學方程式應用題，幫幫忙吧！

4. let the average height of the Great Wall be x m
(x + 1.2) / 6 = 1.5
x +1.2 = 9
x = 7.8
so the average height of the Great Wall is 7.8 m

5. Let the weight of an ink bottle be x g
3x + 8( x/4) = 1000
3x + 2x = 1000
5x = 1000
x = 200
so an ink bottle is 200g

4. Let Y be the average height of the Great Wall.

Y + 1.2 = 1.5 x 6
Y = 9 - 1.2
Y = 7.8

The average height of the Great Wall is 7.8 m.

Prove : Y + 1.2 = 1.5 x 6
7.8 + 1.2 = 9
9 = 9

5. Let Z be the weight of a pen, then 4 Z is the weight of an ink bottle.

8 Z + 3 ( 4Z ) = 1000
8 Z + 12 Z = 1000
20 Z = 1000
Z = 50

The weight of an ink bottle is 4 Z = 4 x 50 g = 200 g.

Prove: 8 Z + 3 ( 4 Z ) = 1000
20 Z = 1000
20 X 50 = 1000

answer:
4.Let y be the average height of the Great Wall
y + 1.2 = 6 X 1.5
y = 9-1.2
= 7.8(m)

5.Let y be the weight of a pen
4y X 3 + 8y = 1000
12y + 8y = 1000
20y = 1000
y= 1000/20
= 50 (g)



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4)
let h be average height of the Great Wall
h+1.2 = (6)(1.5) = 9
h = 9 - 1.2 = 7.8 m
5)
let w be weight of an ink bottle
weight of a pen = w/4
3w + (8)(w/4) = 1000
3w + 2w = 1000
5w = 1000
w = 200 g