Explanation : Let the present age of his daughtcr be x yr and present age of Abhi be y yr.
Then, y = 2x ..... (i)
Five years ago, y - 5 = 4 (x - 5)
Putting the value of Eq.(i) in this
equation, we get
4(x - 5) = 2x - 5
Explanation : x = 1/9; and y = -1/4 (given)
81x2 + 16y2 - 72xy = (9x - 4y)2
= (9x(1/9) - 4x(-3/4))2
(on outputting value of x and y in the equation)
=(1 + 3)2 = 42 = 16
Explanation : Let the cost price be Rs 100/-.
Then, marked price is Rs 140/-.
Selling price = 40% discount on MRP
= 140 -140 x 40⁄100
=140-56
SP = Rs. 84/-
since SP < CP
∴ There is a loss.
Loss percentage = CP - SP⁄CP x 100
= 100 - 84⁄100 x100
= 16% Loss
Explanation : In a right triangle, measure of two sides are 15 cm and 17 cm.
Let the 3rd side of the triangle be 'x' cm
Now, there are two cases,
(i) (15)2 + x2 = (17)2 (as according to the pythagoras theorem)
⇒ 225 + x2 = 289
⇒ x2 = 289 - 225
⇒ x2 = 64
⇒ x = 8cm
(ii) (15)2 + (17)2 = x2
⇒ 225 + 289 =x2 ⇒ x = 514
⇒ x = 2267cm
So, statement B and C are true.
Explanation : Let 2x, 3x, 5x and 8x be the angles of the quadrilateral.
Sum of angles of a quadrilateral = 360 °
⇒ 2x+3x+5x+8x=360o
⇒ 18x=360° ⇒ x=20°
Now, smallest angle = 2x = 2 x 20° = 40o
Complement of the smallest angle = 90o- 40° = 50°...(i)
Largest angle=8x =8 x20o =160°
Supplement of the largest angle= 180° -160° = 20° ... (ii)
Now, sum of the supplement of largest
angle and complement of smallest angle= 20o +50°= 70o