Adi are suma de bani x
x+36=2×Cristi;
x-72=Cristi/2⇒Cristi=2×(x-72)
Cristi=2x-144.
x+36=2×Cristi
Dar Cristi=2x-144 din ambele=> x+36=2×(2x-144)
x+36=4x-288
x-4x=-288-36
-3x=-324
x=-324:(-3)
x=108
Deci, Adi are 108 lei.
Cristi=2x-144
Cristi=2×108-144
Cristi=216-144
Cristi=72 lei.
Sper ca te-am ajutat! :)