Question

15x+3y=39 ; 12x+9y= 51

Answer 1

Step-by-step explanation:

multiply 1 equation by 3,

45 x + 9y = 117

12x + 9y = 51

33x = 66

x = 2

put x in 1,

30 + 3y =39

3 y =9

y = 3

Answer 2

Given Equation:

15x + 3y = 39 ... (i)

12x + 9y = 51 ... (ii)

To Find:

The value of x and y.

Solution:

Subtract eq.i from eq.ii, we get

-3x + 6y = 12

Now divide both the sides by -3, we get

x - 2y = -4

or, x = -4 + 2y ... (iii)

By using eq.iii in eq.i, we get

15( -4 + 2y ) + 3y = 39

or, -60 + 30y + 3y = 39

or, 33y = 99

or, y = 99/33 = 3

By putting the value of y in eq.ii, we get

12x + 9(3) = 51

or, 12x = 51 - 27

or, x = 24/12 = 2

Answer:

The value of x and y is 2 and 3 respectively.