7x-15y=2; x+2y=3

You can do this by using elimination, substitution or cross multiplication method.

1. eqn says-7x-15y+2 nd 2nd eqn says :x+2y =3
   multpy 2nd one wid 7 .  nd den subtrct d eqn u got fm d 1st eqn . ----> 7x-15y-(7x+14y) =2-21 which is eql to -29y =-19 hnce y =19/29 put d value of y in any of d eqnz nd u ll get x.

  by using elimination method-

  7x - 15y = 2  --------------- (1)

  x + 2y = 3  -----------------(2)

  7(x) + 7(2y)  = 3*7   (multiplying the both numbers by 7) ------ (3)

  subtracting the equation (3) from (1)  

  -29y = -19

  y = 19/29

  putting the value of y in equation (2) 

  x + 2 * 19/29 = 3

  x  =  29*3/19*2 = 87/38 ANS.

17x-15y=2

x+2y=3

x=3-2y¨

{by sustitution method}

17{3-2y}-15y=2

51-34y-15y=2

51-2=15y+34y

49=49y

y=1

x=3-2y

x=3-2{1}

x=1

hence x,y=1

s-t=3, s/3=t/2=6