Answer:
y <= 40
Explanation:
Let's call the number of people traveling by van "x", and the number of people buying train tickets "y". We know that the total number of people in the group is 40, so we can write the equation:
x + y = 40
And we also know that the van can hold up to 12 people, so we can write the inequality:
0 <= x <= 12
Now, to find the number of train tickets, we just need to substitute
x = 40 - y into the second inequality:
0 <= 40 - y <= 12
Expanding and solving for y, we get:
0 <= 40 - y <= 12
-40 <= -y <= -28
y >= 28
y <= 40
So the number of train tickets needed (y) is equal to or greater than 28 and equal to or less than 40.