Question

0 . 4 x - 1 . 5 y = 6.5

0.3x + 0.2y = 0.9

( Solve by substitution method )

Answer 1

$\textbf{Solution:}$

$0.4 x- 1.5y = 6.5 - - (1)$

$0.3x + 0.2y = 0.9 - - (2)$

From eq'n ( 1 )

$0.4x - 1.5y = 6.5 \\ \\ = > 0.4x = 6.5 + 1.5y \\ \\ = > x = \frac{6.5 + 1.5y}{0.4} - - (3)$

Substitute eq'n ( 3 ) in eq'n ( 2 )

$0.3x + 0.2y = 0.9 \\ \\ = > 0.3( \frac{6.5 + 1.5y}{0.4} ) + 0.2y = 0.9 \\ \\ = > 1.95 + 0.45y + 0.08y = 0.36 \\ \\ = > 0.53y = 0.36 - 1.95 \\ \\ = > 0.53y = - 1.59 \\ \\ = > y = \frac{ - 1.59}{0.53} \\ \\ = > y = - 3$

From eq'n ( 3 )

$x = \frac{6.5 + 1.5y}{0.4} \\ \\ = > x = \frac{6.5 + 1.5( - 3)}{0.4} \\ \\ = > x = \frac{6.5 - 4.5}{0.4} \\ \\ = > x = \frac{2}{0.4} \\ \\ = > x = 5$

$\textbf{Therefore the value of}$

$\boxed{x = 5 , y = - 3}$

$\textbf{Hope it helps}$

Answer 2

♥️Hi there ♥️

0.4 x - 1 . 5 y = 6.5 -----(1)

0.3x + 0.2y = 0.9---------(2)

$from \: eq \: (1) \: x = \frac{0.9 - 0.2y}{0.3} - - (3)$

Now ,put it in eqn 1

$0.4( \frac{0.9 - 0.2y}{0.3} ) - 1.5y = 6.5$
$0.36 - 0.08y - 0.45y = 1.95 \\ \\ - 0.08y - 0.45y =1.95 - 0.36 \\ \\ - 0.53y = 1.59 \\ \\ y = \frac{1.59}{0.53} \\ \\ y = - 3$
Now put y = -3 in equation (3)

$\frac{0.9 - 0.2( - 3)}{0.3} = \frac{0.9 + 0.6}{0.3} = 5$

Hence ,
$x = 5 \\ \\ y = - 3$
Verification :-

0.4 (5) - 1.5(-3) = 6.5

2+ 4.5 = 6.

Verify ✔️

0.3(5)+0.2(-3) = 0.9

Same with this too.

Thanks !

Hope it will helpful.