I Think The Answer Is 140.
The Expression: 0.8x + x = 252 Can Explain The Answer If x = 140.
Or: 1.8 Times x = 252 If x = 140.

PEMDAS states to do what's in the parenthesis first...

PEMDAS states to multiply 5 by 1 next...

PEMDAS states to subtract 4 by 5 next...

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I hope that helps you out!!
Any more questions, please feel free to ask me and I will gladly help you out!!
~Zoey
Answer:
Adam is the fastest runner
You can convert 2/3 into a fraction that makes adding a lot easier.
Since 3 times 2 is equal to 6, you can multiply the numerator and denominator of 2/3 by 2 to get 4/6.
From there, you add 4/6 + 5/6 to get 9/6.
Since both 9 and 6 are divisible by 3, you can simplify the fraction to 3/2.
Your final answer would be 3/2
Which can also be formatted as 1 1/2 or 1.5