buna ziua! ma puteți ajuta la ex 1?

Răspuns:
Explicație pas cu pas:
x = suma initiala
x = 40x/100 + 60(x -40x/100)/100 +40x/100 -128
x = 4x/10 +6/10*(100x-40x)/100 +4x/10 -128
x = 4x/10 +6/10(60/100) + 4x/10 -128
x = 4x/100 +36x/100 +4x/10 -128
100x =40x +36x +4x -12800
-116x = -128000
116x = 12800, x = 8000
a) 40*8000/100 = 3200
(3200/8000)*100 = 0,4*100 = 40% prima zi
b) 8000 -3200 = 4800
4800*60/100 = 2880 a doua zi