Let the number of students in rooms A and B be x and y respectively.
Then, x - 10 = y + 10
x - y = 20 .... (i)
and x + 20 = 2(y - 20)
x - 2y = -60 .... (ii)
Solving (i) and (ii) we get: x = 100 , y = 80.
The required answer A = 100.
Let the price of a saree and a shirt be ₹x and ₹ y respectively.
Then, 2x + 4y = 1600 .... (i)
and x + 6y = 1600 .... (ii)
Divide equation (i) by 2, we get the below equation.
=> x + 2y = 800. --- (iii)
Now subtract (iii) from (ii)
x + 6y = 1600 (-)
x + 2y = 800
----------------
4y = 800
----------------
Therefore, y = 200.
Now apply value of y in (iii)
=> x + 2 x 200 = 800
=> x + 400 = 800
Therefore x = 400
Solving (i) and (ii) we get x = 400, y = 200.
Cost of 12 shirts = ₹ (12 x 200) = ₹ 2400.
Let number of notes of each denomination be x.
Then x + 5x + 10x = 480
16x = 480
x = 30.
Hence, total number of notes = 3x = 90.
2ab = (a2 + b2) - (a - b)2
= 29 - 9 = 20
ab = 10.
Let the cost of a chair and that of a table be ₹ x and Rs. y respectively.
| Then, 10x = 4y or y = | 5 | x. |
| 2 |
15x + 2y = 4000
15x + 2 x |
5 | x = 4000 |
| 2 |
20x = 4000
x = 200.
| So, y = | ![]() |
5 | x 200 | ![]() |
= 500. |
| 2 |
Hence, the cost of 12 chairs and 3 tables = 12x + 3y
= ₹ (2400 + 1500)
=₹ 3900.
Suppose their paths cross after x minutes.
Then, 11 + 57x = 51 - 63x
120x = 40
| x = | 1 |
| 3 |
Number of floors covered by David in (1/3) min.
| = | ![]() |
1 | x 57 | ![]() |
= 19. |
| 3 |
So, their paths cross at (11 +19) i.e., 30th floor.
Suppose the man works overtime for x hours.
Now, working hours in 4 weeks = (5 x 8 x 4) = 160.
160 x 2.40 + x x 3.20 = 432
3.20x = 432 - 384 = 48
x = 15.
Hence, total hours of work = (160 + 15) = 175.
Let the number of hens be x and the number of cows be y.
Then, x + y = 48 .... (i)
and 2x + 4y = 140
x + 2y = 70 .... (ii)
Solving (i) and (ii) we get: x = 26, y = 22.
The required answer = 26.
Let total number of children be x.
| Then, x x | 1 | x = | x | x 16 x = 64. |
| 8 | 2 |
Number of notebooks :
= |
1 | x2 = | ![]() |
1 | x 64 x 64 | ![]() |
= 512. |
| 8 | 8 |
| (469 + 174)2 - (469 - 174)2 | = ? |
| (469 x 174) |
| Given exp. = | (a + b)2 - (a - b)2 |
| ab |
| = | 4ab |
| ab |
= 4 (where a = 469, b = 174.)

