Question

How do you solve `9x + 5y = 28` and `5x + 9y = 56`?

Answer 1

`x=-1/2; y=13/2`

Explanation:

This can be solved by elimination method. To do this, one can try eliminating x, by multiplying the first equation by 5 and the second equation by 9, then subtracting as follows:
1st eq becomes 45x +25y = 140
2nd eq becomes45x +81y= 504

On subtracting, -56y = -364

Hence y=`364/56 = 13/2`

Using this value of y in the first equation, `9x +5(13/2)=28`

`9x= 28- 65/2`
Or, `9x= -9/2 -> x= -1/2`