A2. Boštjan's sister takes 10 steps to get from the door to the window in the living room. Boštjan's step is $5 \mathrm{~cm}$ longer, so he only takes 9 steps. How many centimeters is Boštjan's step?
(A) 5
(B) 40
(C) 45
(D) 50
(E) Cannot be determined.
A2. Let the length of the sister's step be denoted by $x$, and the length of Boštjan's step by $x+5$. For the same distance, Boštjan took 9 steps, while his sister took 10, so $9(x+5)=10 x$, from which we calculate $x=45$. The length of the sister's step is $45 \mathrm{~cm}$, and Boštjan's is $50 \mathrm{~cm}$.