afla: 924-(150+a)=100-2*100

Răspuns :

924-(150+a)=100+2×100
924-(150+a)=100+200
924-(150+a)=300
150+a=924-300
150+a=624
a=624-150
a=474
==> 924 - ( 150 + a ) = 100 + 2 x 100 
==> 924 - c = 100 + 200   ( am notat 150 + a cu o alta necunoscuta )
==> 924 - c = 300
==> c = 924 - 300
==> c = 624
==> 150 + a = c
==> 150 + a = 624
==> a = 624 - 150
==> a = 474

==> Succes!