Answer:
d = 2.8
Step-by-step explanation:
Isolate the variable. Note the equal sign, what you do to one side, you do to the other. Subtract 7.7 from both sides.
d + 7.7 = 10.5
d + 7.7 (-7.7) = 10.5 (-7.7)
d = 10.5 - 7.7
d = 2.8
d = 2.8 is your answer.
~