480700. The different combinations of students that could go on the trip with a total of 25 student, but only 18 may go, is 480700.
The key to solve this problem is using the combination formula 
. This mean the number of ways to choose a sample of r elements from a set of n distinct objects where order does not matter and replacements are not allowed.
The total of students is n and the only that 18 students may go is r:
Answer:
28j+21
Step-by-step explanation:
remember to isolate the variable. in this case it would be j. after you do that it should be pretty simple
Answer:
4 /15
Step-by-step explanation:
From the number cube :
Count of Numbers greater than 4 = 16
Sample space of number cube = 20
P(number greater than 4) = 16 / 20 = 4/5
Word : ATTENTION
Count of letters in attention = 9
Count of T's in attention = 3
P(choosing T) = 3 / 9 = 1/3
P(greater than 4, then T) = 4/5 * 1/3 = 4 /15
So, how much acid is there in 6 gallons? well is 20% acid or (20/100), so the amount of acid in it just (20/100) * 6 or 1.2, the rest is say water.
now, if we want a 90% solution, and say we add "y" gallons, how much acid is in it? well (90/100) * y, or 0.9y.
now let's add "x" gallons of pure acid, now, pure acid is just pure acid, so is 100% acid, how much acid is there in it? (100/100) * x, or 1x or just x.
we know whatever "x" and "y" amounts are, they -> x + 6 = y
and we also know that x + 1.2 = 0.9y
