Question

solve it by substitution method:- 5x - 6y=-9 & 3x + 4y= 25.

Answer 1

Substitution method

Given equations are -5x-6y = -9 ---> (1)

3x+4y = 25

Subtract 3x from each side.

4y = -3x+25

divide to each side by 4.

y = (-3x+25)/4 ---> (2)

Substitute the y value in (1).

-5x-6(-3x+25)/4 = -9

-5x-3(-3x+25)/2 = -9

-5x+(9x-75)/2 = -9

[-10x+9x-75]/2 = -9

Multiple to each side by 2.

-x-75 = -18

Add 75 to each side.

-x = -18+75

-x = 57

Multiple to each side by negitive one.

x = -57

Substitute the x value in (2).

y = (-3*-57+25)/4

y = 196/4

y = 49

Solution x = -57& y = 49.