How many Kilos of almonds are there?

Question

A mixture of almonds and raisins sells for $2.25/kg. Almonds are $9/kg. Raisins are $1.50/kg. If a 20kg mixture will be created, "how many kg of this mixture are almonds?"

Answer 1

X + Y = 20

 

9X + 1.50Y = 20*2.25

 

9X + 1.50(20-X) = 20*2.25

 

9X + 30 - 1.5X = 45

 

7.5X = 15

X=2

 

2 kg of almonds and 18 kg of raisins

 

 

Answer 2

a + r = 20 ----> a = 20 - r

9a + 1.5r = 2.25(20)

9(20 - r) + 1.5r = 45

180 - 9r + 1.5r = 45

7.5r = 135

r = 18

 

a = 20 - 18

a = 2