Problem to Solve Simultaneous Equation

Topic : Simultaneous Equation

Question : Solve for x and y,
8x - 3cy = 9c
12x - 7cy = - 39c

Solution :
8x - 3cy = 9c------- (1)
12x - 7cy = - 39c----(2)
Multiply equation (1) by 3 and (2) by 2
24x - 9cy = 27c
24x -14cy = -78c
-------------------
00 + 5cy = +105c (divide both sides by 5c)
So y = 21

Substituting the Value of y in equation (1)
8x - 3c(21) = 9c
8x-63c = 9c (adding +63c on both sides)
8x = 72c
x = 9c