Mathematics
If ∠A = 2x°, ∠B = (6y + 10)°, ∠C = (2x + y)° and ∠D = (x + 10)° are the angles of a quadrilateral, then the values of x and y will be :
x = 40°, y = 20°
x = 20°, y = 40°
x = 45°, y = 15°
x = 15°, y = 45°
Linear Equations
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Answer
We know that,
Sum of all interior angles of a quadrilateral = 360°.
⇒ ∠A + ∠B + ∠C + ∠D = 360°
⇒ 2x° + 6y° + 10° + 2x° + y° + x° + 10° = 360°
⇒ 5x° + 7y° + 20° = 360°
⇒ 5x° + 7y° = 340°
Substituting x = 40°, y = 20° in L.H.S. of the above equation, we get :
⇒ 5 × 40° + 7 × 20°
⇒ 200° + 140°
⇒ 340°.
Since, L.H.S. = R.H.S.
Solution : x = 40°, y = 20°.
Hence, option 1 is the correct option.
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Case Study I Ritesh bought a new well-furnished two-bedroom flat in a society. The layout of the flat is shown in the figure alongside. The builder claims that the areas of the two bedrooms and the kitchen together is 95 square metres. All the dimensions in the figure are in metre (m).

Study the above information and answer the following questions.
Which of the following pair of linear equations represent the given situation?
(a) x + y = 19, 2x + y = 13
(b) x + y = 13, 2x + y = 19
(c) x − y = 19, 2x − y = 13
(d) x + y = 13, 2x − y = 19The perimeter of the outer boundary of the layout is:
(a) 54 m
(b) 27 m
(c) 50 m
(d) 52 mTotal area of bedroom 1 and kitchen is:
(a) 60 m2
(b) 70 m2
(c) 65 m2
(d) 95 m2The area of the living room is:
(a) 50 m2
(b) 60 m2
(c) 70 m2
(d) 75 m2The cost of laying tiles on the floor of the kitchen at the rate of ₹200 per sq m is:
(a) ₹ 7,000
(b) ₹ 6,000
(c) ₹ 5,200
(d) ₹ 5,000
Case Study II
There are two mobile-phone companies – P and Q, that offer different plans. Company P charges a monthly fee of ₹ 40 plus ₹ 0.5 per minute of talk time. Company Q charges a monthly service fee of ₹ 30 plus ₹ 1 per minute of talk time.
Based on this information answer the following questions:
The linear equation which expresses the plan of company P is :
(a) y = 0.5x + 40
(b) y = 40x + 0.5
(c) y = x + 40.5
(d) y = 40 − 0.5xThe linear equation which expresses the plan of company Q is:
(a) y = 30x + 1
(b) y = x + 30
(c) y = x − 30
(d) y = 30x − 1How many minutes of talk time would yield equal expenditure from both companies?
(a) 10 minutes
(b) 15 minutes
(c) 20 minutes
(d) 25 minutesManisha took the plan of company P and used 400 minutes of talk time. She spent:
(a) ₹240
(b) ₹430
(c) ₹220
(d) ₹215If in a month, Anurag wants to use only 300 minutes of talk time, then which company’s plan is better for him?
(a) Company P
(b) Company Q
(c) Both offer the same plan
(d) Can’t be determined