Question

Solve the following pair of linear equations by the substitution method

$s-t=3,\frac{s}{3}+\frac{t}{2}=6$

• A. $s=2,t=7$
• B. $s=9,t=6$
• C. $s=3,t=1$
• D. $s=6,t=-9$

Answer 1

Answer: (B)

$s=9,t=6$

$s-t=3$.....(i)
$\frac{s}{3}+\frac{t}{2}=6$.....(ii)
From (i) $s=t+3$ ...(iii)
Substituting s from (iii) in (ii), we get
$\frac{t+3}{3}+\frac{t}{2}=6$
$\Rightarrow 2(t+3)+3t=36$
$\Rightarrow 5t+6=36$
$\Rightarrow t=6$
From (iii), $s=6+3=9$,
Hence, $s=9,t=6$