中1maths 問題
2008-08-22 11:02 pm
For the electricity bill, water bill and gas bill received last month, Mr.Ho paid $1000more on the electricity bill than on the water bill, and the water bill was $160 less than 2 times the gas bill. If Mr. Ho paid a total amount of $2080, how much was the electricity bill?
回答 (2)
2008-08-22 11:18 pm
✔ 最佳答案
Let x , y and z be the amount of gas bill, water bill and electric bill respectivelyy = 2x - 160 --------(1)
z - y = 1000 ---------(2)
sub (1) into (2):
z - 2x + 160 = 1000
z = 2x + 840 --------(3)
x + y + z = 2080 -----------(4)
sub (3) and (1) into (4):
x + (2x - 160) + (2x+840) = 2080
5x = 1400
x = 280
from (3):
z = 2x + 840 = 2(280) + 840 = 1400
electric bill is $1400
2008-08-22 11:27 pm
Let x be the gas bill.
Then the water bill = 2x-160.
And the electricity bill = 2x-160+1000
The gas bill+the water bill+the electricity bill = 2080
So, x+2x-160+2x-160+1000 = 2080
5x-320+1000 = 2080
5x-320 = 2080-1000
5x = 1080+320
5x = 1400
5x÷5 = 1400÷5
x = 280
The electricity bill = 2x-160+1000 = 1400
So, the electricity bill is $1400.
Hope I can help you~!!! =]
Then the water bill = 2x-160.
And the electricity bill = 2x-160+1000
The gas bill+the water bill+the electricity bill = 2080
So, x+2x-160+2x-160+1000 = 2080
5x-320+1000 = 2080
5x-320 = 2080-1000
5x = 1080+320
5x = 1400
5x÷5 = 1400÷5
x = 280
The electricity bill = 2x-160+1000 = 1400
So, the electricity bill is $1400.
Hope I can help you~!!! =]
參考: Myself
收錄日期: 2021-04-13 16:26:45
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