Afati nr x pentru care:3×{10+2×[40-2×(28-3×5)]}-7x=51
va rog urgent dau coroana


Răspuns :

3×[10+2×(40-2×13)]=51+7x
3×(10+2×14)=51+7x
3×38=51+7x
114=51+7x
7x=114-51
7x=63
x=63:7
x=9