They could have assembled total 336 different possible crews.
<em><u>Explanation</u></em>
Total number of trained pilots is 9 and geologists is 4.
The crew should be consisted of 2 pilots and 1 geologist. That means, <u>2 pilots are chosen from total 9 and 1 geologist is chosen from total 4</u>.
Number of ways for choosing 2 pilots from 9 and
Number of ways for choosing 1 geologist from 4
So, the total possible number of different crews they could have assembled
a + b ≥ 30, b ≥ a + 10, the system of inequalities could represent the values of a and b
option A
<u>Step-by-step explanation:</u>
Here we have , The sum of two positive integers, a and b, is at least 30. The difference of the two integers is at least 10. If b is the greater integer, We need to find which system of inequalities could represent the values of a and b . Let's find out:
Let two numbers be a and b where b>a . Now ,
According to the given statement we have following inequality :
⇒
According to the given statement we have following inequality :
⇒
⇒
⇒
Therefore , Correct option is A) a + b ≥ 30, b ≥ a + 10