i dont have great difficulty in rearranging simultaneous equations with an x and y value equals a number but when a third value is put in things confuse me : im trying to rearrange this formula

y = 8 - 2x
x + y + 7 = 0

ive rearranged the top one to y + 2x = 8

the second one i dont no what to do with the zero ? my attempt is x + y = 0 - 7

 

Quite right. Can you solve the system now?

 

maths guru is that a yes your answer is right ( keep all cons together) then i can solve the "system"

 

Yes, I said that your assumption about putting the '7' on the right hand expression was correct. Your new system should be:

\(\left\ \begin{array}{l} y+2x=8 \\ x+y=-7\\
\end{array} \right}\)

Can you handle that system? Do you need any more help?

 

just what i was looking for