A situation is given. Represent it in the form of linear equations. 5 books and 7 pens together cost ₹ 79 whereas 7 books and 5 pens together cost ₹ 77. Here consider cost of each book as ₹ x and that of each pen as ₹ y.
(a) 17x + 7y = 79, 5x + 5y = 77 (b) 5x + 7y = 79, 7x + 5y = 77
(c) 5x + 5y = 79, 7x + 7y = 77
(d) Data insufficient
Answers
Answer:
its helpful
Explanation:
Let the cost of 1 book =x
And the cost of 1 pen =y
⇒5x+7y=79
⇒7x+5y=77
Equation (1) × 7 : 35x+49y=79×7
Equation (2) × 5 : 35x+25y=77×5
Subtract two equations ;
⇒24y=168
⇒y=7
⇒x=6
Total cost of 1 book and 2 pens =x+2y=6+14=20
Explanation:
Given that 5 books and 7 pens together cost ₹ 79 whereas 7 books and 5 pens together cost ₹ 77.
Also said that consider cost of each book as ₹ x and that of each pen as ₹ y.
From above we can say that cost of 5 books is 5x and cost of 7 pens is 7y. And the sum of 5 books and 7 pens is ₹ 79.
As per above statement,
→ 5x + 7y = 79
Similarly,
Cost of 7 books is 7x and cost of 5 pens is 5y. And the sum of 7 books and 5 pens is ₹ 77.
From above statement we can write,
→ 7x + 5y = 77
Therefore, the linear equations are (5x + 7y = 79) and (7x + 5y = 77)
Hence, option b) 5x + 7y = 79, 7x + 5y = 77 is correct.