Answer:
[tex] \pink{ \pmb{SOLUTION:-}}[/tex]
Here,
[tex]\displaystyle{ \frac{6 + x}{16 + x} = \frac{36 + x}{76 + x} }[/tex]
[tex](6 + x)(76 + x) = (36 + x)(16 + x)[/tex]
[tex]456 + 6x + 76x + {x}^{2} = 576 + 36x + 16x + {x}^{2} [/tex]
[tex]82x + 456 = 576 + 52x[/tex]
[tex]82x - 52x = 576 - 456[/tex]
[tex]30x = 120[/tex]
[tex]\displaystyle{x = \frac{120}{30} }[/tex]
[tex]{ \rightarrow{ \pmb{x = 4}}}[/tex]