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一題代數題(20分)(急!!!!!!!!!)

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14 There are 300 coins in a box. x of them are 50￠ coins and the rest are $2 coins. The total value of the coins is $270. (a) Find the value of x. (b) Hence, find the number of $2 coins in the box. 分開兩題計呀!!!!!!!

最佳解答:

(a) The number of $2 coins = (300 - x). 0.5 * x + 2 * (300 - x) = 270 => 0.5x + 600 - 2x = 270 => 600 - 1.5x = 270 => 1.5x = 600 - 270 => x = 330 / 1.5 => x = 220 ....... (i) The value of x is 220. (b) 300 - x = 300 - 220 = 80 ...... by (i) The number of $2 coins in the box is 80.

其他解答:

I think you all have miss a point in question B. The coins are 2 dollars coins,so it should be: 300-220÷2 =80÷2 =40 So,the number of $2 coins in the box should be 40.|||||a)0.5x+2(300-x)=270 0.5x+600-2x=270 1.5x=330 x=220 so,the value of x is$220 b)300-220 =80 so,the number of $2 coins in the box are 80|||||a)0.5x+2(300-x)=270 0.5x+600-2x=270 1.5x=330 x=220 b)300-220 =80|||||a) 0.5x +2(300-x)=270 x=220 b) 300-220=80|||||a) 0.5x +2(300-x)=270 x=220 b) 300-220=8063D0B758E2D502CC