Given:
1. Peter works as a teaching assistant and gets paid on a weekly basis.
2. He gets paid D dollars per hour for the first 30 hours and (D+ 10) dollars per hour for the hours worked in excess of 30 hours.
Asked: What is the value of D?
(1) Last week Peter worked for 32 hours.
Peter gets paid = 30D + 2(D+10) = $(32D + 20)
Value of D can not be derived.
NOT SUFFICIENT
(2) Peter got paid $8(D+10) more if worked for 40 hours instead of 32 hours.
Peter gets paid for 32 hours = 30D + 2(D+10) = $ (32D + 20)
Peter gets paid for 40 hours = 30D + 10(D+10) = $ (40D + 100)
Difference = 8D + 80 = $8(D+10)
The statement does not provide any additional information, value of D can not be derived.
NOT SUFFICIENT
(1) + (2)
(1) Last week Peter worked for 32 hours.
Peter gets paid = 30D + 2(D+10) = $(32D + 20)
(2) Peter got paid $8(D+10) more if worked for 40 hours instead of 32 hours.
Peter gets paid for 32 hours = 30D + 2(D+10) = $ (32D + 20)
Peter gets paid for 40 hours = 30D + 10(D+10) = $ (40D + 100)
Difference = 8D + 80 = $8(D+10)
Since both statements do not provide any information about D.
NOT SUFFICIENT
IMO E