Let Dennis thought of a number = P
step 1:- He adds 0.5 to number , then number = P + 0.5
Step 2:- 4 is multiplied with (P + 0.5) , e.g., 4(P + 0.5) = 4P + 2
Step 3 :- 2 is Subtracted from (4P + 2) ,e.g., 4P + 2 - 2 = 4P
Step 4 :- 2 divides 4P by 2 e.g., 4P/2 = 2P
Step 5 :- his final answer is 2P = 48
⇒ 2P = 48
⇒ P = 24
Hope that help!