Answer:
D) 25
Step-by-step explanation:
The ∑ of all interior angles of a triangle = 180°.
Set the measurements of each given angle equal to 180:
m∠D + m∠E + m∠F = 180
(4x) + (2x - 3) + (x + 8) = 180
First, simplify by combining like terms. Like terms are terms with the same amount of the same variables:
4x + 2x - 3 + x + 8 = 180
(4x + 2x + x) + (-3 + 8) = 180
7x + 5 = 180
Next, isolate the variable, x. Note the equal sign, what you do to one side, you do to the other. Do the opposite of PEMDAS. PEMDAS is the order of operations, and stands for:
Parenthesis
Exponents (& Roots)
Multiplication
Division
Addition
Subtraction
-
First, subtract 5 from both sides of the equation:
7x + 5 (-5) = 180 (-5)
7x = 180 - 5
7x = 175
Next, divide 7 from both sides of the equation:
(7x)/7 = (175)/7
x = 175/7
x = 25
D) 25 is your value for x.
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