Solution:

Your friend's statement is actually true and it's not different from what you have answered.

25 - 55 + (85 + 65) = 25 - 55 + 150 = 120 = 5!
5! (factorial) = 5 * 4 * 3 * 2 * 1 = 120

Yes, that was a tricky question, quite capable to confuse anybody.

Solution:

The remaining time is 15 minutes.

Since, 1/5 part of the time you have spent is left, the total time is 6 parts.

The total time is 90 minutes. 1/6 of 90 = 15.

Therefore, 15 minutes are remaining.

Solution:

There can be three cases for this question.
1) X and Y are present in the same row.
In this case, Y will be the tallest in the row => Y is taller than X.

2) X and Y are present in the same column.
In this case, X will be the shortest of the column => Y is taller than X.

3) X and Y are present in different rows and different columns. Suppose that the child standing in X’s column and Y's row is Z. Then:
Y is taller than Z and Z is taller than X => Y is taller than X.

Therefore, in any of the above cases, Y is taller than X.

Solution:

In the given statement, the letters represent their equivalent position in the alphabets.
A + A = 1 + 1 = 2 = B
B + B = 2 + 2 = 4 = D
A + D = 1 + 4 = 5 = E

Hence,
B + D + E = 2 + 4 + 5 = 11 = K

Solution:

34293

Solution:

1/6227020800

Explanation
This can be solved through a simple mathematical equation.

N cards have n! permutations.
Therefore, the probability of obtaining a specific one by chance is 1/n!

Now, in this particular case, n = 13
Therefore, the required probability is 1/6227020800

Solution:

19(snake) + 1(Echidna) + 80(Bird) Egg =>100 eggs.
Cost:
19*5 + 1 + 4 =>100 pence

Solution:

5 plates.

Explanation
Let's say A is the number of plates washed successfully and B is a number of plates got broken in the cleaning process.
3A – 9B = 240
A + B = 100
=> B=5 (answer) , A(95)

Solution:

   9567
+ 1085
======
 10652

Solution:

3.4142788e+29

The biggest number using four 2s will be:
22^22