Hi guys, got a question here that i can't seem to make sense The sum of the first 12 terms of an AP is 222, the sum of the first 5 terms is 40. Write out the first four terms of the series. Right I'm using te Sn=n/2[2a+(n-1)d] equation to form a simultaneous equation to work out a and d: 222=6[2a+11d] 40=5/2[2a+4d] Multiplying the brackets leaves me with: 222=12a+66d 40=5a+10d Multiplying the first one by 5 and the second by 12 to get a common a of 60 lets me find d, but it doesn't give me the right answer. for the record, a is 2 and d is 3, but i can't get those answers. I know I've obviously done something silly, or might even be doing the completely wrong thing, can someone point me in the right direction please?