The question (i) Simplify the following expression as far as possible, showing all your work- ing: 7y - 12 - 3y + 32. (ii) Solve the following equation, showing all your working: (t + 9) = 28. The student's incorrect attempt: (L ) Given: zy - 12 - 34+ 32 Group Like terms: = zy - 34 - 12 + 32 Collect Like terms: = 44+ 20 Subtract 20: - 20 = 4y Divide by 4: - 5 = y The solution is y = - 5. (LL) Given: = (t + 9 ) = 28 clear the fraction: 2(t + 45) = 140 Multiply by 2: 2t + 90 = 140 Subtract 90: 2t = 50 Divide by 2: t = 25 The solution is t = 25.{a} The student has made a mistake in both parts of their attempt. Identify these mistakes and explain, as if directly to the student. why. for each mistake, their reasoning is incorrect. {b} 'Write out your own solution to each part of the question, explaining your working. [4] [5] (c) The student decides to check if the solution they got to part (ii) of the question was correct using the following approach: Check: Substitute 25 for t: ( t + 9 ) = 28 Work out the brackets: ( 34 ) = 28 68 Giving: = 28 5 This is incorrect so the solution t = 25 is incorrect. (1) Explain why the approach to checking that they have chosen is incorrect. (2) Show how the student should have performed the check