Answer:
134
Step-by-step explanation:
The ratio of Type O donors to total donors was ...
... 37 : (37+43) = 37 : 80
So, 37/80 is the fraction of total donors that were Type O.
Then the number of Type O donors expected in a group of 290 is ...
... (37/80) · 290 = 134.125 ≈ 134