Tick (✓) the correct answer:

(a) 67

$(a-b)=7$

$\Rightarrow$ Squaring both the sides :

$\Rightarrow(a-b)^{2}=(7)^{2}$

$\Rightarrow\left(a^{2}+b^{2}-2 a b\right)=49$

$\Rightarrow\left(a^{2}+b^{2}\right)=49+2 a b$

$\Rightarrow\left(a^{2}+b^{2}\right)=49+2(9)$

$\Rightarrow\left(a^{2}+b^{2}\right)=49+18$

$\Rightarrow\left(a^{2}+b^{2}\right)=67$