Posted by Omotimehin pelumi on .
Using a cramers and guassian elimination method solve this;
a+2b+3c=600
2a+3b+c= 900
3a+b+2c=800

Maths 
Steve,
D = 18
Dx = 3500
Dy = 2900
Dx = 1100
I'll let you do the elimination; come on back if you get stuck, and show where things went south.