Please take a look at the picture.

Answer:
Step-by-step explanation:
[tex] = > b - \frac{7}{4} = - \frac{2}{3} [/tex]
[tex] = > b = - \frac{2}{3} + \frac{7}{4} [/tex]
[tex] = > b = \frac{ - 8 + 21}{12} [/tex]
[tex] = > b = \frac{13}{12} \: or \: 1 \frac{1}{12} [/tex]