I hope that 2-1 means 21.
DE + EF = DF
4x + 10 + 21 = 9x - 15
4x + 31 = 9x - 15
31 = 9x - 4x - 15
31 = 5x - 15
46 = 5x
x = 9 1/5 = 9.2
You want 9x - 15
9*9.2 - 15
82.8 - 15
67.8 <<<<< answer.
If I have given the wrong meaning to 2-1 (which could mean 1) leave another note and I will correct my work.
A $20 decrease followed by a $20 increase - original value
A 75% decrease followed by a 50% increase - less than the original value
A 50% increase followed by a 33 1/3% decrease - greater than the original value
A 60% increase followed by a 40% decrease - greater than the original value
A 100% increase followed by a 33 1/3% decrease - greater than the original
The equivalent expression to given expression is 1/3.
<h3>What is Equivalent Expression?</h3>
Equivalent expressions are defined as algebraic expressions which give the same resulting expression. An algebraic expression (or) a variable expression is defined as a combination of terms by the operations such as addition, subtraction, multiplication, division.
Here, given expression

= 
= 
= 1/3
Thus, the equivalent expression to given expression is 1/3.
Learn more about equivalent expression from:
brainly.com/question/24242989
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