Given :
A 2.8 m ladder is to be laid against a wall so that the top of the ladder is 2 m up the wall.
To Find :
How far out from the base of the wall should the ladder be placed.
Solution :
We know, the angle between floor and height is 90° .
Now, length of ladder, l = 2.8 m .
Height of wall, h = 2 m .
Let, distance between base of the wall and ladder is b .

Hence, this is the required solution.
Since we are trying to find the adult seats, we'll set that to x. Now the student section is 2x + 25. The total seats is 130 which is the student section and adult section added together. So now we can write an equation from the information given...
Students + adults = 130
(2x + 25) + x = 130
2x +25 +x = 130
2x + x + 25 = 130
3x + 25 = 130
3x = 130 - 25
3x = 105
x = 105/3 = 35
So there are 35 adult seats (remember we set adults to x)
Now we substitute back into the equation to find the students seats. As you recall students = 2x + 25
Students = 2x + 25
Students = 2(35) + 25
Students = 70 + 25
Students = 95
There are 95 student seats and 35 adult seats.
Subtract 2 from each side of the equation, and
the answer will be right there, staring up at you.
Go ahead. It'll be very helpful for you.