Eighty seven written in standard form would be...
80 + 7 = 87
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A,d,b, and then c ,basically least to greatest
Answer:
x = 12
Step-by-step explanation:
The diagram shows an equilateral triangle (because all angles are congruent). All sides in equilateral triangle are congruent, so

Solve the equation

Check this value:

Thus, 
For the first question: The equation would be set up as 30=1/2(12x) Then solve for x. (Or just plug that formula into Desmos)
Answer: x=5