Olivia and Isabella each earn d dollars for each dog she walks. One day, Olivia walks 6 dogs and gets $8 in tips. That same day, Isabella walks 9 dogs and gets $12 in tips.
a. Olivia writes 6d + 8 + 9d + 12 to represent the amount
they earn together. Isabella writes 5(3d + 4). Are their
expressions equivalent? Show your work.