use equation
1.$5400is divided among three persons:A ,B and C. A gets twice the amount of B,while C gets $600 more then 3 times B`s amount.How much does each of them get?
2.City A is 100 km to the west of city B.David rides a bicycle 15 km/h from city A to the west. At the same time,Alice deives a car y km/h from city B to the west.
(a) Express ,in trerms of y ,the distance between David and Alice after 2 hours.
(b)If Alice catches up with David after 2.5 hours,find the value of y.
I want to ask Maths
2007-10-14 12:20 am
回答 (2)
2007-10-14 12:31 am
✔ 最佳答案
1. Let $x be the amount that B gets.Then, A gets $2x and C gets $(3x+600)
x+2x+3x+600 = 5400
6x = 4800
x = 800
B gets $800, A gets $1600 and C gets $3000
2.(a) After 2 hours, David rides 30 km and Alice travels 2y km.
Distance between David and Alice 100+30 - 2y = (130 - 2y) km
(b) After 2.5 hours, David travels 37.5 km and Alices travels 2.5y
100+37.5-2.5y = 0
2.5y = 137.5
y = 55
2007-10-14 1:14 am
1. Let $a B gets.
A =$2a,B =$a, C =$3a+600
2a +a +(3a +600) =5400
2a +a +3a +600 =5400
6a +600 =5400
6a =6000
a =1000
Therefore, B has $1000.
Hence, A has 2 x1000= $2000, C has 3 x1000 +600 =$3600
2a. Because 15 x2= 30km/h,
David will ride 30 km after 2 hours.
Alice will drive 2y km after 2 hours
Then, the remain= 100mk -30km= 70km
then their distance= 70-2y km
2b. After 2.5 hours,
David rides : 15 x2 + 15 ÷2= 30+7.5= 37.5 km
Alice drives : 2y + y÷2 = 100 -37.5 km= 62.5 km
2y + y/2 =62.5
2(2y + y/2 )=(62.5)2
4y +y =125
5y =125
y =25
Hope i can help u^^~
A =$2a,B =$a, C =$3a+600
2a +a +(3a +600) =5400
2a +a +3a +600 =5400
6a +600 =5400
6a =6000
a =1000
Therefore, B has $1000.
Hence, A has 2 x1000= $2000, C has 3 x1000 +600 =$3600
2a. Because 15 x2= 30km/h,
David will ride 30 km after 2 hours.
Alice will drive 2y km after 2 hours
Then, the remain= 100mk -30km= 70km
then their distance= 70-2y km
2b. After 2.5 hours,
David rides : 15 x2 + 15 ÷2= 30+7.5= 37.5 km
Alice drives : 2y + y÷2 = 100 -37.5 km= 62.5 km
2y + y/2 =62.5
2(2y + y/2 )=(62.5)2
4y +y =125
5y =125
y =25
Hope i can help u^^~
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