Astudent is asked to calculate the value of 212 − 132 using the identity x2 − y2 = (x − y)(x + y). the student's steps are shown below. step 1: 212 − 132 = (a − b)(a + b) step 2: = (c)(d) step 3: = (8)(30) + 8(4) step 4: = 240 + 32 step 5: = 272 what are the values of a, b, c, and d?