Question

12.
By solving equation 3x + 4y = 25 and 4x + 3y = 24 with the help of cross multiplication method,
we obtain (x÷a)=(y÷b)=(1÷c) then the value of (a + b)÷c is equal to
(A) 2
(B)3
(D) 6
(C) 7​

Answer 1

Answer:

7

Step-by-step explanation

4×[3x + 4y = 25]

3×[4x + 3y = 24]

so we get

12x+16y=100--{1}

12x+9y=72   --{2}

{1}-{2} subtracting 2 from 1

we get

7y=28; y=4   --{3}

now substituting 3 in 1

we get x=3

according to the question

x/a=y/b=1/c   [substitute values of x y in this]

we see

3/a=4/b=1/c ; cross multiplying first two equations we get

3/4=a/b ; ∴ a=3;b=4 and equating 4/b=1/c ; c= 1.

therefore the answer is 7.