標題:
Please solve S1 maths
發問:
Sam had a number of $1 and $5 coins. It was known that half the number of $1 coins was greater than the number of $5 coins by 2. If the total value of the coins was $32, how many $1 coins and how many $5 coins did Sam have?
最佳解答:
This can be done by setting up two eqts and solve them at the same time: x : no. of $1 coins, y : no. of $5 coins x+5y=32 x/2-y=2 After solving: x=12, y=4 12 $1 and 4 $5
其他解答:
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Let the no. of $1 coins be x Let the no. of $5 coins be y Then, we have: (1) x/2-y=2 (2) x + 5y =32 Change (1) to x-2y =4 ....(3) (2)-(1): 7y = 28 y = 4 put y=4 into (2) x+ (5 X 4) = 32 x = 12 Hence Sam has twelve $1 coins and four $5 coins. ------------------------------------------------------------------------------------------------------ p.s. "how many $1 coins and how many $5 coins did Sam have? " Should be "...Sam has"|||||Sam had a number of $1 and $5 coins. It was known that half the number of $1 coins was greater than the number of $5 coins by 2. If the total value of the coins was $32, how many $1 coins and how many $5 coins did Sam have? assume he has x $1 coins and $5 coins has x/2 – 2 x + 5(x/2 – 2) = 32 x + 5x/2 – 10 = 32 2x + 5x – 20 = 64 7x = 84 x = 12 $5 coins = 12/2 - 2 = 4 so he has 12 $1 coins and 4 $5 coins|||||let x be the number of $1 coin then,there are(x-2) $5 coins x+5(x-2)=32 x+5x-10=32 6x=42 x=7 so he has 7 $1 coins and 5 $5 coins
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