Question

Solve the following pair of equation by substitution method 7X-15y=2
X+2y=3

Answer 1

7 x -15 y =2................1
x + 2 y =3....................2
let us consider the equation ......1
                         x+2y=3
write it as 
                         x=3-2y .......................3 
substitute the value of x in equation ....1
             7(3-2y)-15y=2
             21-14y-15y=2
               21-29y=2
              -29y=-19
                 y=19/29
substitute the value of y in equation ..3
           x=3-2(19/29)
         x=49/29
∵x=49/29
  y=19/29
              
      

Answer 2

Answer:

$7x - 15y = 2 \\ \: \implies7x = 2 + 15y \\ \implies \: x = \frac{2 + 15y}{7} \: \: \: \: \: \rightarrow(i) \\ \\ x + 2y = 3 \\ \implies\frac{2 + 15y}{7} + 2y = 3 \: (putting \: x = \frac{2 + 15y}{7} ) \\ \implies \frac{2 + 15y + 14y}{7} = 3 \\ \implies15y + 14y = 3 \times 7 - 2 \\ \implies29y = 21 - 2 \\ \implies \: y = \frac{19}{29} \\ \\ \\ \: \: substituting \: the \: value \: of \: y \: in \: equation \: (i) \\ 7x - 15 \times \frac{19}{29} = 2 \\ \implies7x - \frac{285}{29} = 2 \\ \implies7x = 2 + \frac{285}{29} \\ \implies7x = \frac{58 + 285}{29} \\ \\ \: \implies7x = \frac{343}{29 } \\ \\ \implies \: x = \frac{343}{203} \\ \\ \implies \: x = \frac{49}{29} \\ \\ \therefore \: x = \frac{49}{29} \\ \\ y = \frac{19}{29}$