Question

Dennis thinks of a number. He adds 0.5 to that number and then multiplies the new result by 4. He then subtracts 2 and divides the number by 2. His final answer is 48. What number did Dennis start with?

Answer 1

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Answer 2

let the number be X

{ [(X + 0.5 ) × 4 ] -2 } /2 = 48

[(X + 0.5 ) × 4 ] -2 = 48 × 2

[(X + 0.5 ) × 4 ] = 96 +2

[(X + 0.5 ) × 4 ]  = 98

(X + 0.5 ) = 98/4

(X + 0.5 ) = 24.5

X = 24.5 - 0.5

X = 24

Therefore, Dennis started with the number "24"