»f(x) = 9x + 7
»f(b) = 16
»f(b) = 9b + 7
»16 = 9b + 7
»16 - 7 = 9b
»9b = 9
»b = 9/9
»b = 1✅
[tex]\\ \rm\hookrightarrow f(b)=16[/tex]
[tex]\\ \rm\hookrightarrow 9b+7=16[/tex]
[tex]\\ \rm\hookrightarrow 9b=9[/tex]
[tex]\\ \rm\hookrightarrow b=1[/tex]