D. [tex] \frac{21 \: b}{10} - 48[/tex] ✅
Step-by-step explanation:
[tex] - 6( \frac{1}{4} b+ 10) + 4( \frac{9}{10}b + 3) \\ = \frac{ - 6 \: b}{4} - 60 + \frac{36 \: b}{10} + 12 \\ = \frac{ - 3 \: b}{2} + \frac{18 \: b}{5} - 60 + 12 \\ = \frac{ - 3 \: b \times 5}{2 \times 5} + \frac{18 \: b \times 2}{5 \times 2} - 48 \\ = \frac{ - 15 \: b + 36 \: b}{10} - 48 \\ = \frac{21 \: b}{10} - 48[/tex]
[tex]\circ \: \: { \underline{ \boxed{ \sf{ \color{green}{Happy\:learning.}}}}}∘[/tex]
