Question

solve the following equations by substitution method 5x 3y=21;2x-y=4

Answer 1

$5x +3y=21$  &  $2x - y=4$

5x+3y=21
2(5x + 3y)=2 x 21
10x + 6y=42
10x = 42 - 6y...(i)

2x - y=4
5(2x-y)=4
10x-5y=4
10x=4+5y...(ii)

So, 42 - 6y= 4 + 5y
      42 -  4 = 6y+5y
      38 = 11y
      y=38/11

10x= 4+ 5*38/11
10x  = 44/11 + 190/11
x= 234/11
x=2340/11