Question 4 (b) - Figure it out - Page 185 to 189 - Chapter 7 Class 7 - Finding the Unknown (Ganita Prakash II)

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Question 4 (b) Here are machines that take an input, perform an operation on it and send out the result as an output. Find the inputs in the following cases:We assume Input = x If we follow our machine Input gets multipled by 3, so 3 × x = 3x Input gets added by 3, so x + 3 Both these values are subtracted: 3x – (x + 3) = 3x – x – 3 = 2x – 3 Thus, we write Output = 2x – 3 Now, solving our equation First equation Our equation is Output = 2x – 3 Since Output = 63, our equation becomes 63 = 2x – 3 Putting –3 on left side, it becomes + 3 63 + 3 = 2x 66 = 2x Putting 2x on left side 2x = 66 Putting 2 on right side, so it becomes division x = 66/2 x = 33 Thus, input is 33 Second equation Our equation is Output = 2x – 3 Since Output = 227, our equation becomes 227 = 2x – 3 Putting –3 on left side, it becomes + 3 227 + 3 = 2x 230 = 2x Putting 2x on left side 2x = 230 Putting 2 on right side, so it becomes division x = 230/2 x = 115 Thus, input is 115