Explicație pas cu pas:
[(a+260:2)×3+5]×5=2005
(a+130)×3+5=2005:5
(a+130)×3+5=401
(a+130)×3=401-5
(a+130)×3=396
a+130=396:3
a+130=132
a=132-130
a=2
