Pattern help, please. Decrease Round

I am knitting a Sunbeam Angel Top (592), which I have made twice before.

This time, I am knitting the second size and have adapted it for ITR. It is bottom-up and in st-st.

I can’t get my head round the Back decrease. I have completed the Front half of the dec rnd - the decs were worked differently, either side of a central panel.

I have 87sts for the Back, and they should decrease to 55sts.

Can someone, please, put this in simpler terms for me, or just offer easier decs?

This is the line (all Ps will be converted to K, for ITR):

[B]K1, P2 (P2 tog.) 4 times, * P2, (P2 tog.) 3 times, * rep. from * to * 3 times, P1 (P2 tog.) 3 times, rep. from * to * 4 times, P2 tog., P2, K1. (55sts.)[/B]

Both halves (of the Back) should be symetrical, around a centre st, which is later BO, for the placket.

Thank you, in advance, for anyone with time to help.