Answer:
10 ; 22
Explanation:
Ghana = G
Cameroon = C
Cameron only = 8
Ghana only = 12
Total sampled = 40
Both Ghana and Cameroon = x
Not traveled to either = 10
Ghana only + Cameroon only + both Ghana and Cameroon + not traveled to either = total sampled
12 + 8 + x + 10 = 40
30 + x = 40
x = 40 - 30
x = 10
Number that had gone to Ghana before :
Ghana only + both
12 + x
12 + 10
= 22