S.1 Maths文字體(10分)

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let john has saved $x , and his sister has saved $y,
John's savings is $300 more than his sister's

改動過: =>y=x-300--(1)

After giving $450 from his savings to his sister, John's savings becomes 2 /5 of his sister's

(2/5)(y+450)=x-450

2y+900=5x-2250

5x-2y=3150--(2)



put (1) into (2)

5x-2y=3150

5x-2(x-300)=3150

改動過: 3x+600=3150

改動過: 3x=2550

改動過: x=850

改動過: y=x-300=850-300=550//

改動過: so john has saved $850 , and his sister has saved $550

additional verify:
john = 850 = 550 + 300 = sister + $300
john - 450 = 850 - 450 = 400 = (2/5) * 1000 = (2/5) * 550+450
= (2/5) * (sister + 450 )
希望幫到你

let john has saved $x , and his sister has saved $y,
John's savings is $300 more than his sister's
=>y=x+300--(1)
After giving $450 from his savings to his sister, John's savings becomes 2 /5 of his sister's
(2/5)(y+450)=x-450
2y+900=5x-2250
5x-2y=3150--(2)

put (1) into (2)
5x-2y=3150
5x-2(x-300)=3150
3x-600=3150
3x=3750
x=1250
y=x-300=1250-300=950//
so john has saved $1250 , and his sister has saved $950