As Ghana developed economically, education of the citizenry progressed apace.  In 1890 there were only 5 government and 49 "assisted" mission schools in the whole of the Gold Coast with a total enrollment of only 5,000. By 1920 there were 20 governmental schools, 188 "assisted" mission and 309 "unassisted" mission schools with a total enrollment of 43,000 pupils. By 1940, there were 91,000 children attending Gold Coast schools. By 1950, the 279,000 children attending some 3,000 schools in the Gold Coast. This meant that, in 1950, 43.6% of the school-age children in the Gold Coast colony were attending school.
Question: How many more "assisted" mission schools were there in 1920 compared to 1890?
Answer: 139