Question

Using substitution method solve the equation X+2y=21,x-y=9

Answer 1

${\red{\huge{\mathcal{\star{Hey{\star}}}}}}$

${\boxed{\huge{\bf{\pink{x=13}}}}}$

${\boxed{\huge{\bf{\pink{y=4}}}}}$

steps-

${\bf{\underline{Given-}}}$

$x - y = 9 \\ x + 2y = 21$

from (1),

$x = 9 + y$

substitute in (2),

$9 + y + 2y = 21 \\ 3y = 21 - 9 \\ 3y = 12 \\ y = 4$

substitute in (1),

$x - 4 = 9 \\ x = 9 + 4 \\ x = 13$

Hope it helps you ✌❤

Answer 2

$\bf\huge\red{Answer}$

Equations -

x + 2y = 21 --- (1)

x - y = 9 --- (2)

x = 9 + y --- (3)

Substitute (3) equation in (1) equation

Therefore,

9 + y + 2y = 21

9 + 3y = 21

3y = 21 - 9

3y = 12

y = 12/3

=> 4

Thus, y = 4 --- (4)

Now, to find x value, substitute y = 4 in equation (2)

Thus,

x = 9 + y

x = 9 + 4

x = 13

Answer -

$\bf{Value\:of\:x\:=\:13}$

$\bf{Value\:of\:y\:=\:4}$