Question

Find the value of z, if $3(5z-7)-2(9z-11)=4(8z-13)-17$.

• A. $z=2$
• B. $z=4$
• C. $z=6$
• D. $z=7$

Answer 1

The correct option is A $z=2$

$3(5z-7)-2(9z-11)=4(8z-13)-17$
$\Rightarrow 15z-21-18z+22=32z-52-17$
$\Rightarrow -3z+1=32z-69$
$\Rightarrow -3z-32z=-69-1$
$\Rightarrow -35z=-70$
$\Rightarrow z=2$

Let's verify by substituting z = 2 in the given equation.
$3(5z-7)-2(9z-11)=4(8z-13)-17$
$\Rightarrow 3\left[\right(5\times 2)-7]-2\left[\right(9\times 2)-11]=4\left[\right(8\times 2)-13]-17$
$\Rightarrow 3[10-7]-2[18-11]=4[16-13]-17$
$\Rightarrow (3\times 3)+(-2\times 7)=(4\times 3)-17$
$\Rightarrow 9-14=12-17$
$\Rightarrow -5=-5$
$\Rightarrow LHS=RHS$
Therefore, it is correct.