An easy? dumb logic i can't figure out

CFA Level II Fixed Income
#1

Say company x invests in a structured security backed by bond or mortgage.

Beg Accrual 97,337
Total amount of interest income received 37,481
Ending Accrual 21,048
Interest Received 113,770

I don’t quite understand that means. Does that mean the initial (coupon or interest) accumulated is 97k, then during this period 113k of coupon or interest payment is received. So 97k of that 113k is attributable to prior period’s accrual which gives us 16k remaining (113- 97). Then there’s additional 21k accrual in current month so the 16k + 21k = 37k interest ?

I just don’t follow and the person who explained this wasn’t very clear.

#2

Where did you find this ? Quite the source please

#3

It sounds as though they earned 37,481 in interest this period, but were paid 113,770 in interest this period. Some of what they were paid was earned in previous periods, and accrued.

At least, that’s how the numbers resolve.