Solve by elimination method.

5x+3y=-7
7x-2y=19

I know that y= 43/31, but I do not know what I am supposed to do when I plg 43/31 in for x in the equation... the answer they came up with is ;
43/31, -144/31 How do you get -144?

Question

Solve by elimination method.

5x+3y=-7
7x-2y=19

I know that y= 43/31, but I do not know what I am supposed to do when I plg 43/31 in for x in the equation... the answer they came up with is ;
 43/31, -144/31    How do you get -144?

anonymous · Answer

x=43/31
plug x value into one of the equation

5(43/31)+3y=-7
215/31+3y=-7
3y=-7-(215/31)
3y=(-217-215)/31
3y=-432/31
y=-432/(3*31)
y=-144/31

anonymous · Answer

Oh i see now, thank you :D

anonymous · Answer

how did yo get 217?

anonymous · Answer

$$\frac{-7}{1}-\frac{215}{31}$$
lcd=31
$$\therefore ,\frac{(-7)(31)-215}{31}$$$$\frac{217-215}{31}$$

anonymous · Answer

okay so multiplty -7x31.. lol thanks  :D

anonymous · Answer

yup 
np :D