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1. 2 watermelons and 8 orange cost $104. If a watermelon $27 more than an orange, find the cost of an orange.
2. There are 700 rabbits and chickens in a farm. They have 1 900 legs altogether. How many chickens are there?
Math問~幫幫我手..(English)
2008-12-24 5:53 am
回答 (2)
2008-12-24 7:54 am
✔ 最佳答案
Q1Let $x be the cost of an orange
then the cost of a watermelon = $(x+27)
8x+2(x+27)=104
8x+2x+54=104
10x+54=104
10x=104-54
10x=50
x=5
∴The cost of an orange is $5
Q2
Let x and y be the number of rabbits and chickens in the farm respectively
x+y=700--------------(1)
4x+2y=1900---------(2)
From (1),
x=700-y--------------(3)
Substitute (3) into (2),
4x+2y=1900
4(700-y)+2y=1900
2800-4y+2y=1900
2800-2y=1900
2800-1900=2y
900=2y
2y=900
y=450
∴There are 450 chickens in the farm
2008-12-24 6:03 am
1) let x be the cost of an orange
the cost of a watermelon is x+27
8x+2(x+27)=104
8x+2x+54=104
10x=50
x=5
the cost of an orange is $5
2) let there are y chickens and z rabbits
we have y+z=700----(1)
and 2y+4z=1900-----(2)
from (1)
y+z=700
z=700-y----------------(3)
put (3)into (2)
2y+4(700-y)=1900
2y+2800-4y=1900
-2y=-900
2y=900
y=450
there are 450 chickens in the farm.
the cost of a watermelon is x+27
8x+2(x+27)=104
8x+2x+54=104
10x=50
x=5
the cost of an orange is $5
2) let there are y chickens and z rabbits
we have y+z=700----(1)
and 2y+4z=1900-----(2)
from (1)
y+z=700
z=700-y----------------(3)
put (3)into (2)
2y+4(700-y)=1900
2y+2800-4y=1900
-2y=-900
2y=900
y=450
there are 450 chickens in the farm.
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