HOMEWORK....HELP2方程

1.Bobby saves a fixed amount of money every day.He finds that the price of a model is \$70 more than his savings in 5 days or \$10 more than his saving in 9 days.How much does he save each day?

2.A sum of \$120 is divided between two sisters.The eldae sister spends 1/5 of the amount recived while the younger sister spends 1/6 of the amount recived.If the eldersister spends\$13 more than the younger sister,how much does each of them recived?

D式可唔可以詳細D...

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• Amby
Lv 6

1.Bobby saves a fixed amount of money every day.He finds that the price of a model is \$70 more than his savings in 5 days or \$10 more than his saving in 9 days.How much does he save each day?

let x be the money he saves per day

5x+70=9x+10

4x=60

x=15

so he saves \$15 per day

2.A sum of \$120 is divided between two sisters.The eldae sister spends 1/5 of the amount recived while the younger sister spends 1/6 of the amount recived.If the eldersister spends\$13 more than the younger sister,how much does each of them recived?

let elder sister recieved \$x,then young sister recieved \$(120-x)

x*(1/5)=(120-x)*(1/6)+13

x/5=(120-x)/6+78/6

x/5=(120-x+78)/6

x/5=(198-x)/6

5(198-x)=6x

990-5x=6x

990=11x

x=90

so elder sister recieved \$90 and younger sister recieved \$30

(1)

let x be the money he saves per day

5x+70=9x+10

4x=60

x=15

so he saves \$15 per day.

(2)

let elder sister recieved \$x,then young sister recieved \$(120-x)

x*(1/5)=(120-x)*(1/6)+13

x/5=(120-x)/6+78/6

x/5=(120-x+78)/6

x/5=(198-x)/6

5(198-x)=6x

990-5x=6x

990=11x

x=90

so elder sister recieved \$90 and younger sister recieved \$30.

Source(s): myself
• Anonymous

1. Let \$x be the fixed amount of money every day,

70+5x = 10+9x

4x = 60

x = 15

so the amount is \$60

2006-10-19 20:06:11 補充：

\$15 is corect.