Explicație pas cu pas:
[(b+5)x5+5]×5+5=205
[(b+5)×5+5]×5=205-5=200
[(b+5)×5+5]=200÷5=40
(b+5)×5=40-5=35
(b+5)=35÷5=7
b+5=7
b=7-5
b=2