The mission was of 225 days.
We are informed from the question the percentage of bad days and number of bad days. So, relating the two parts of question will give the number of days explorers were on mission. Let us assume the total number of days of mission be x.
20% × x = 45
Solving the equation now -
20/100x = 45
Shifting 100 to Right Hand Side of the equation as denominator
20x = 45 × 100
Performing multiplication on Right Hand Side of the equation
20x = 4500
Shifting 20 to denominator on Right Hand Side of the equation
x = 4500 ÷ 20
Performing division on Right Hand Side of the equation
x = 225
Hence, explorers were on mission for 225 days.
Learn more about percentage calculation -
https://brainly.com/question/24877689
#SPJ4