Răspuns :
100(2x+1) + 50(3x-1) = 400
200x + 100 + 150x - 50 = 400
200x + 150x = 400 - 100 + 50
350x = 350
x = 1
.................................
q.e.d.
200x + 100 + 150x - 50 = 400
200x + 150x = 400 - 100 + 50
350x = 350
x = 1
.................................
q.e.d.