The work of a student to solve a set of equations is shown:

equation a: y = 4 – 2z
equation b: 6y = 2 – 4z

step 1: –6(y) = –6(4 – 2z) [equation a is multiplied by –6.]
6y = 2 – 4z [equation b]
step 2: 6y = 4 – 2z [equation a in step 1 is simplified.]
6y = 2 – 4z [equation b]
step 3: 0 = 6 – 6z [equations in step 2 are added.]
step 4: 6z = 6
step 5: z = 1

in which step did the student first make an error?
step 4
step 3
step 2
step 1

Leslie started last week with $1200 in her checking account. during the week, she wrote the checks below. trans typ./ check no. date description of transaction payment/ debit deposit/ credit (+) balance 1,200 00 324 10/6 miller's food market 45.87 45 87 groceries 1,154 13 325 10/7 cyber center computer outlet 218.59 218 59 monitor 935 54 326 10/9 sandy's beauty salon 30.00 30 00 haircut and styling 900 59 deposit 10/10 paycheck 621.33 621 33 1,621 92 evaluate leslie's check register. a. leslie did a good job. everything is correct. b. the final balance is wrong; she did not add everything correctly. c. leslie should have written debit instead of deposit for the transaction type. d. leslie switched the debit and credit columns.