# Thread: Mixture Problem equation issue

1. ## Mixture Problem equation issue

There are 2 brands of fertilizers containing nitrogen and water. Gentle green is 5% nitrogen and sun saver is 15% nitrogen. We need to combine two types of solutions in order to make 100 litres of 12% nitrogen. How much of each brand should be used?

0.05x + 0.15x = 0.05 + 0.15 ( 100 + 0.12 )

Is that equation correct ?

2. ## Re: Mixture Problem equation issue

no

$0.05 g + 0.15 s = 0.12(100) = 12$

$g + s = 100$

you can take it from there

3. ## Re: Mixture Problem equation issue

0.5g + 0.15s = 12 ( 100 )

g + s =100 ( - 50 )

50g + 15s = 1200
-50g = 50s = -5000

-35s = - 3800

s = 108.571

4. ## Re: Mixture Problem equation issue

you got s = 108.571 > 100

Originally Posted by diehardmath4
0.05g + 0.15s = 12 ( 100 )

g + s =100 ( - 5 )
try again ...

5. ## Re: Mixture Problem equation issue

0.05G + 0.15s = 0.12 ( 100 )

G + S = 100 ( -5 )

5g + 15s = 12
-5g - 5s = -500

10s = -488

s = - 48.8

6. ## Re: Mixture Problem equation issue

Originally Posted by diehardmath4
0.05G + 0.15s = 0.12 ( 100 )

G + S = 100 ( -5 )

5g + 15s = 12
-5g - 5s = -500

10s = -488

s = - 48.8
dude....

$G+S=100$

$G = 100-S$

$0.05G + 0.15S = 12$

$5G + 15S = 1200$

$5(100-S) + 15S = 1200$

$500- 5S+ 15S = 1200$

$10S = 700$

$S = 70$

$G = 100-70=30$

7. ## Re: Mixture Problem equation issue

0.05g + 0.15s = 12 ( 100 )

g + s =100 ( - 5 )
5g + 15s = 1200

-5g - 5s = -500

10s = 700

s = 70

g = 30

8. ## Re: Mixture Problem equation issue

Originally Posted by skeeter
5g + 15s = 1200

-5g - 5s = -500

10s = 700

s = 70

g = 30
why did that -5 get in there?

9. ## Re: Mixture Problem equation issue

Originally Posted by romsek
why did that -5 get in there?
Multiplying the second equation to eliminate the g term ... the OP originally multiplied by (-50)