標題:
maths ^^^^vvv^^^
發問:
1. the cost of a ruler is four times that of a rubber.if the total cost of a ruler and a rubber is $15,find the cost of a rubber.2. jim's father is now 10 times jim's age.in eight year's time,his age will be four times jim's age.how old is jim now?3. jane has 15 coins which include... 顯示更多 1. the cost of a ruler is four times that of a rubber.if the total cost of a ruler and a rubber is $15,find the cost of a rubber. 2. jim's father is now 10 times jim's age.in eight year's time,his age will be four times jim's age.how old is jim now? 3. jane has 15 coins which include $2-coins and $5-coins only.if the total value of $2-coins is less than that of $5-coins by $33,how many $5-coins does jane have?
1. let x be the cost of a rubber 4x + x = 15 5x = 15 x = 15/5 x = 3 therefore, the cost of a rubber is $3 2. let y be Jim's age 4*(y+8) = 10y+8 4y+32 = 10y+8 32-8 = 10y-4y 24 = 6y y = 24/6 y = 4 therefore, Jim now is 4 years old 3. let x be the number of $5 coins 2(15-x) + 33 = 5x 30-2x+33=5x 30+33 = 5x+2x 63 = 7x x = 63/7 x = 9 therefore, Jane has 9 pieces of $5 coin 2010-11-02 19:47:30 補充： 回覆001 第二條唔知你問咩==in eight year's time???? in eight year's time = 8年後
其他解答:
1.Let x be the cost of a rubber 4x+x=15 x(4+1)=15 x(5)=15 x=3 3.Let x and y be the No.of $2-coins and $5-coins respectively x+y=15...(1) 5y-2x=33...(2) (1)X2, 2x+2y=30...(3) (2)+(3) 5y-2x+(2x+2y)=33+30 5y-2x+2x+2y=63 7y=63 y=9 Put y=9 into (2) 5(9)-2x=33 45-2x=33 -2x=-12 x=6 So:Jane has 9 $5-coins. 第二條唔知你問咩==in eight year's time????
maths ^^^^vvv^^^
發問:
1. the cost of a ruler is four times that of a rubber.if the total cost of a ruler and a rubber is $15,find the cost of a rubber.2. jim's father is now 10 times jim's age.in eight year's time,his age will be four times jim's age.how old is jim now?3. jane has 15 coins which include... 顯示更多 1. the cost of a ruler is four times that of a rubber.if the total cost of a ruler and a rubber is $15,find the cost of a rubber. 2. jim's father is now 10 times jim's age.in eight year's time,his age will be four times jim's age.how old is jim now? 3. jane has 15 coins which include $2-coins and $5-coins only.if the total value of $2-coins is less than that of $5-coins by $33,how many $5-coins does jane have?
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最佳解答:1. let x be the cost of a rubber 4x + x = 15 5x = 15 x = 15/5 x = 3 therefore, the cost of a rubber is $3 2. let y be Jim's age 4*(y+8) = 10y+8 4y+32 = 10y+8 32-8 = 10y-4y 24 = 6y y = 24/6 y = 4 therefore, Jim now is 4 years old 3. let x be the number of $5 coins 2(15-x) + 33 = 5x 30-2x+33=5x 30+33 = 5x+2x 63 = 7x x = 63/7 x = 9 therefore, Jane has 9 pieces of $5 coin 2010-11-02 19:47:30 補充： 回覆001 第二條唔知你問咩==in eight year's time???? in eight year's time = 8年後
其他解答:
1.Let x be the cost of a rubber 4x+x=15 x(4+1)=15 x(5)=15 x=3 3.Let x and y be the No.of $2-coins and $5-coins respectively x+y=15...(1) 5y-2x=33...(2) (1)X2, 2x+2y=30...(3) (2)+(3) 5y-2x+(2x+2y)=33+30 5y-2x+2x+2y=63 7y=63 y=9 Put y=9 into (2) 5(9)-2x=33 45-2x=33 -2x=-12 x=6 So:Jane has 9 $5-coins. 第二條唔知你問咩==in eight year's time????
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