Australia pledged half a billion dollars to restore and protect the Great Barrier Reef Sunday in what it said would be a game-changer for the embattled natural wonder.
Japan Today

HINTS
S Australia
V [pledged] 約束した
O half a billion dollars 5億ドル
[to restore [and] protect] the Great Barrier Reef グレートバリアリーフを元に戻して保護

[in what]

S it
V [said]

S
V [would be]
O a game-changer
どんな→
[for] the embattled natural wonder.