中一方程式(應用題)

1) Let x kg be the weight of the sheep.
x+(50+x)+100+(50+x)=620
x+50+x+100+50+x =620
200+3x =620
3x =620-200
3x =420
x =140

∴ The weight of the pig is 190kg and the weight of the cow is 290kg.

∴ The weight of the sheep is 140kg , the weight of the pig is 190kg and the weight of the cow is 290kg .

1) Let x kg be the weight of the sheep.
x+(50+x)+100+(50+x)=620
x+50+x+100+50+x =620
200+3x =620
3x =620-200
3x =420
x =140

∴ The weight of the pig is 190kg and the weight of the cow is 290kg.

1)A farmer raises a cow,a pig and a sheep.The cow is 100kg heavier than the pig.The pig is 50kg heavier than the sheep.The total weight of the cow, the pig and the sheep is 620kg.Find their respective weights

let the weight of sheep is X kg, the weight of pig is (X+50)kg and the weight of cow is (X+50+100)kg

X + X + 50 + X + 50 + 100 = 620
3X = 420
X = 140

∴ The weight of the sheep is 140 kg, the weight of the pig is190 kg and the weight of the cow is 290 kg.

2)Kenny spent $82 on 12 pens made in Hong Kong and Japan.The pens made in Hong Kong are $6 each,while those made in Japan are $8 each.Find the number of each type of pens bought by Kenny.

let the number of pen made in hong kong be X, the pen made in japan be Y.

X + Y = 12 -----(1)
6X + 8Y = 82 -----(2)

from(1), X = 12-Y -----(3)
sub. (3) into (2), 6(12-Y) + 8Y = 82
72 - 6Y + 8Y = 82
2Y = 10
Y = 5

sub. Y=5 into (1), X + 5 = 12
X = 7

∴He bought 5 pens made in Japan.

∴He spent $42 on pens made in Hong Kong and $40 on pens made in Japan.

∴ Kenny bought 7 pens in Hong Kong and 5 pens made in Japan.