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math_dude16
Mar 13, 2009, 08:37 AM
Could someone please help me! This problem with elimination not SUBSITUTION:

Nn+ Nd= 50
5Nn+10Nd= 450

galactus
Mar 13, 2009, 01:16 PM
N is a constant and n and d are the variables.

Nn+Nd=50
5Nn+10Nd=450

Multiply the top equation by -5. See why? We have to find a number that eliminates a variable. In this case, -5+5=0. So, we have:

-5Nn-5Nd=-250
5Nn+10Nd=450

Add them:

5Nd=250

d=\frac{50}{N}

Now, you find n.

asastring
Mar 13, 2009, 06:57 PM
5Nd = 200
d=40/N