How to solve Simultaneous Equations by Elimination - example

How to solve Simultaneous Equations by Elimination.

[stevenhenderson]

Thank you so much for the fast methods. I past my Aircraft engineering exam first time😉. We not aloud to use calculators and pass mark is 75%. Thank you so much I got 86% for my exam

[sm]

Thank u sm uve helped me thru all my math midterms

[Vintage_Aesthetic]

Just learnt this elimination method in 10th grade!
Substitution method confuses me a bit. I know how to do it but I just can't seem to solve it correctly in the end somehow, idk why T-T

[kevinpusceddu]

For the first substitution how do you know which part (1) or (2) of the equation you multiply by to find x.