Answer:

Step-by-step explanation:
here's the solution :-
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Let the amount Tom does = x
Then Larissa’s time would be 3x( 3 times the amount of Tom)
And Neal would also be 3x
The total of the 3 is 84 hours so as an equation you have:
X + 3x + 3x = 84
Combine like terms
7x = 84
Divide both sides by 7
X = 84/7
X = 12 hours
Tom = x, so Tom exercised for 12 hours.
2. Angle Addition Postulate as they are adding both angles
3. 60 + 40 = m <ABC because it's a substitution
4. 100 = m <ABC as it is simplified already
5. Definition of obtuse angle