Question

suma a doua nr. naturale este 700 iar diferenta 140 . aflati nr.

Answer 1

a+b=700
a-b=140
==>a=700-b
==>700-b-b=140
==>-2b=140-700
==>-2b=-560
==>b=280
a+280=700
==>a=700-280
==>a=420

Answer 2

$a+b=700 \\ a-b=140 \to \boxed{a=140+b} \\ ********************* \\ \\ 140+b+b=700 \\ \\ 140+2b=700 \\ \\ 2b=700-140 \\ \\ 2b=560 \\ \\ b=280 \\ \\ a+280=700 \to a=420$