The most common scenario was the low-fuel landing. It was there in 25 % of the tests. The number of tests was 25+115=140 tests (adding up the failed and passed test.
So to find our how many were trained in the most common scenario, we have to calculate25% of 140.
25/100*140=(i calculate frist 25/100. I divide both by 25, we have 1/4)1/4*140 = In order to calculate this, we need to divide 140/4. This is:
35____140:4 12 20 20 ==
so the correct answer is 35.