A little rusty, but this is my opinion.

.25x+1y+.50z= 10700
.35x+1.50y+.50z=15820
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.60x+2.5y+1z=26520

I would get rid of decimals by multiplying by 10
10 (.6x+2.5y+z)=26520(10)
6x+25y+10z=265200

Now, solve for each variable so you are using common factors.
x=(265200-25y-10z)/6

((265200-25y-10z)/6))+25y-10z=265200

etc... It will work out this way.

OR
Plug the factors into the matrix function on your calculator.