Answer:
cost per unit of gas i.e y= 0.36
Step-by-step explanation:
Let cost per unit of electricity = x
and cost per unit of gas = y
The equations required will be:
![600x+100y=390 ---- eq(1)\\400x+250y=326----eq(2)](https://tex.z-dn.net/?f=600x%2B100y%3D390%20----%20eq%281%29%5C%5C400x%2B250y%3D326----eq%282%29)
We need to find value of y i.e cost per unit of gas
Solving equations to find value of y
We will use elimination method
Multiply equation 1 by 4 and 2 by 6
![2400x+400y=1560 ---- eq(1)\\2400x+1500y=1956----eq(2)](https://tex.z-dn.net/?f=2400x%2B400y%3D1560%20----%20eq%281%29%5C%5C2400x%2B1500y%3D1956----eq%282%29)
Subtracting eq 1 from eq 2
![2400x+1500y=1956----eq(2)\\2400x+400y=1560 ---- eq(1)\\- \ \ \ \ \ - \ \ \ \ \ \ \ \ \ \ -\\----------------\\1100y=396\\y=\frac{396}{1100}\\y=0.36](https://tex.z-dn.net/?f=2400x%2B1500y%3D1956----eq%282%29%5C%5C2400x%2B400y%3D1560%20----%20eq%281%29%5C%5C-%20%5C%20%5C%20%5C%20%5C%20%5C%20-%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20-%5C%5C----------------%5C%5C1100y%3D396%5C%5Cy%3D%5Cfrac%7B396%7D%7B1100%7D%5C%5Cy%3D0.36)
Solving we get y=0.36
Putting value of y in eq(1) to find value of x
![600x+100y=390\\600x+100(0.36)=390\\600x+36=390\\600x=390-36\\600x=354\\x=\frac{354}{600}\\x=0.59](https://tex.z-dn.net/?f=600x%2B100y%3D390%5C%5C600x%2B100%280.36%29%3D390%5C%5C600x%2B36%3D390%5C%5C600x%3D390-36%5C%5C600x%3D354%5C%5Cx%3D%5Cfrac%7B354%7D%7B600%7D%5C%5Cx%3D0.59)
Value of x = 0.59
But we need to find only cost of unit of gas i.e y
So, cost per unit of gas i,e y= 0.36