Question

suma a 2 nr este 30.daca marim primul nr cu suma lor obtinem de 9 ori al 2 nr.Care sunt nr?

Answer 1

a+b = 30

a+(a+b) = 2b => a+30 = 9b => a = 9b - 30

9b-30 + b = 30 => 10b = 60 => b = 60:10 => b = 6

a = 9 x 6 -30 = 54-30 = 24

a = 24 ; b = 6

Answer 2

$Faci~asa~:~\begin{cases} \\ a+b=20\\ \\ 2a+b=9b\\~\\\end{cases}\\ \\ a=4b\\ \\ 5b=20~\xrightarrow{\text{dupa~ce~imparti~vei~avea}} ~\boxed{\text{b=4}}\\ \\ Din~relatia~a=4b~\xrightarrow{\text{Inlocuiesti~b=4~fiindca~l-ai~aflat~deja~si~vei~avea}}~\boxed{\text{a=16}}$