Given pairs of equations are:
(i) 3x + 2y = 10 and 4x + 3y – 9 = 0
3x + 2y = 10 ... eq1
And,
4x + 3y = 9 ... eq2
After multiplying equation 1 by 4, and equation 2 by 3 we get:
4 × (3x + 2y = 10) and 3 × (4x + 3y = 9)
12x + 8y = 40 ... eq3
And,
12x + 9y = 27 ... eq4
Subtracting equation 4 from equation 3 we get:
y = -13
Putting y = -13 in equation 3, we get:
12x + 8(-13) = 40
12x – 104 = 40
12x = 40 + 104
12x = 144
x = 12
This is not the required set of equations as the value of y is negative.
(ii) 5x + 2y + 4 = 0 and 2x + 3y + 6 = 0
5x + 2y = -4 ... eq 1
And,
2x + 3y = -6 ... eq 2
After multiplying equation 1 by 2 and equation 2 by 5 we get:
2 × (5x + 2y = -4) and 5 × (2x + 3y = -6)
10x + 4y = -8 ... eq 3
And,
10x + 15y = -30 … eq 4
Subtracting equation 3 from equation 4, we get:
y = -2
Putting y = -2 in equation 3, we get:
10x + 4(-2) = -8
10x – 8 = -8
10x = -8 + 8
10x = 0
x = 0
This is not the required set of equations as value of y is negative.
(iii) 2x +

y = 9 and x + 5y –

= 0

= 9 and x + 5y =
4x + 3y = 2 × 9 and 2(x + 5y) = 3
4x + 3y = 18 ... eq1
And ,
2x + 10y = 3 ... eq2
After multiplying equation 1 by 2 and equation 2 by 4 we get:
2 × (4x + 3y = 18) and 4 × (2x + 10y = 3)
8x + 6y = 36 ... eq 3
And,
8x + 40y = 12 ... eq4
Subtracting equation 3 from equation 4, we get:

y =
y =
Putting y =

in equation 3, we get:
8x + 6(

) = 36

= 36
136x – 72 = 612
136x = 612 + 72
136x = 684
x =
This is not the required set of equations as the value of y is negative.
(iv)

and
5(x – 3) = y + 2 and 1(10y + x) = 4(y + x)
5x – 15 = y + 2 and 10y + x = 4y + 4x
5x – y = 2 + 15 and 10y – 4y = 4x – x
5x – y = 17 and 6y = 3x
5x – y = 17 and x = 2y
Putting x = 2y in (5x – y = 17), we get:
5(2y) – y = 17
10y – y = 17
9y = 17
y =
We know that,
x = 2y
Therefore, x = 2 ×
x =
For this pair of equations, the solutions for 'x' and 'y' are positive rational numbers.
Hence, option 3 is the answer.