Answer:
$120 is the minimal amount to pay
Step-by-step explanation:
36 students are equivalent to to 4 groups (3 of ten people and 1 of six people). This is $30 X 4 = $120
If we should choose 3 groups of ten people and 6 individual people, we'd pay
$30 X 3 = $90 (this for 3 groups of 10 people)
$6 X 6 = $36 (this for 6 individual people)
Then $90 + $36 = $126
