Question

y-x=7,y+2x=43 система

Answer 1

y-x=7. 43-2x-x=7. 43-3x=7.
y=43-2x, y=43-2x, y=43-2x,
-3x=-36. x=12. x=12
y=43-2x, y=43-2*12, y=19