Question

how can we solve the problem 2x+y=1;3x-4y=18

Answer 1

see , these r two linear equations with 2 variables . so there r three methods to do it :
(1) substitution 
(2) elimination
(3) cross multiplication 
here i am solving this by substitution
so , 2x+y=1
       from here , y=1-2x  ------------(1)
putting (1) in 3x - 4y =18 
so, 3x - 4(1-2x) = 18
      3x - 4 +8x = 18
      11x - 4 = 18
      11x = 22
      dividing by 11
      x = 2  -------------(2)
putting (2) in (1)
y=1-2(2)
y=-3

Answer 2

2x+y=1(1 equation)
3x-4y=18(2 equation)
since in 2nd equation has 4y multiply the first equation with 4, u get
(8x+4y=4)+(3x-4y=18) u get
8x+4y=4
3x-4y=18
+4y and -4y get cancelled we get 11x=22 so x = 2
substitute x=2 in (1st or second equation)
so we get
2(2)+y=1
4+y=1
y=1-4
y= -3
so x=2 and y= -3
pick my answer as the best plz!!!!!!!!!!!