I believe RSv5 workbook solution missed BGP->EIGRP redistribution on R1 and R4 without redistribution on this routers BGP route is still use even shows AD 200 due to we dont have this route in EIGRP.
R4#sh ip route 150.1.77.77
Routing entry for 150.1.77.77/32
Known via "bgp 100", distance 200, metric 0
Tag 200, type locally generated
Last update from 155.1.45.5 00:22:30 ago
Routing Descriptor Blocks:
* 155.1.45.5, from 155.1.45.5, 00:22:30 ago
Route metric is 0, traffic share count is 1
AS Hops 2
Route tag 200
MPLS label: none