On the first part of the test (Section A) Alex scored 55% of 80 marks.
He got 55% of 80 = 44 marks.
On the second part of the test (Section B) we assume that Alex scores 100% (we need the greatest percentage).
On the Section B he got 60 marks.
60 + 44 = 104
The greatest percentage:
140 × x = 104
(max points on the test × the percentage = the number of marks Alex got)
x = 104/140
x = 0.7428 = 74.3%