Question

Rahul's Dad became happy seeing the equation he made to find the value of "x” using the perimeter of the house. So, he gave a few equations to Rahul and asked him to solve the equations. What values of $x$ should he get? [3 MARKS]
(i) $4x+5=25$
(ii) $x-2\frac{1}{3}=5\frac{1}{2}$
(iii) $(7x+8)÷7=8$

Answer 1

Each Option: 1 Mark

(i) $4x+5=25$
$\Rightarrow 4x=25-5$
$\Rightarrow 4x=20$
Divide by 4 on both sides,
$4x÷4=20÷4$
$x=5$

(ii) $x-2\frac{1}{3}=5\frac{1}{2}$
$\Rightarrow x-\frac{7}{3}=\frac{11}{2}$
$\Rightarrow \frac{3x-7}{3}=\frac{11}{2}$
$\Rightarrow 3x=\frac{11}{2}\times 3+7$
$\Rightarrow 3x=\frac{33+14}{2}=\frac{47}{2}$
$\Rightarrow x=\frac{47}{6}=7\frac{5}{6}=7.833$

(iii) $(7x+8)÷7=8$
$\Rightarrow \frac{7x+8}{7}=8$
$\Rightarrow 7x=8\times 7-8=56-8=48$
$\Rightarrow x=\frac{48}{7}=6\frac{6}{7}=6.86$