Question

Difficulty: MediumSolving Linear Equations

If xx is a real number that satisfies the equation 35(2x7)+0.4=0.2(x+3)\frac{3}{5}(2x - 7) + 0.4 = 0.2(x + 3), what is the value of 5x25x - 2?

Answer: 20

Answer

The value of the expression 5x25x - 2 is 2020.
First, convert the fraction 35\frac{3}{5} to the decimal 0.60.6. The equation becomes 0.6(2x7)+0.4=0.2(x+3)0.6(2x - 7) + 0.4 = 0.2(x + 3). Distribute on both sides to get 1.2x4.2+0.4=0.2x+0.61.2x - 4.2 + 0.4 = 0.2x + 0.6. Combine constant terms on the left side to get 1.2x3.8=0.2x+0.61.2x - 3.8 = 0.2x + 0.6. Subtract 0.2x0.2x and add 3.83.8 to both sides to isolate the variable, resulting in x=4.4x = 4.4. Finally, substitute x=4.4x = 4.4 into the expression 5x25x - 2 to get 5(4.4)2=222=205(4.4) - 2 = 22 - 2 = 20.

Step-by-Step Solution

1
Convert the fraction and distribute the coefficients
1.2x4.2+0.4=0.2x+0.61.2x - 4.2 + 0.4 = 0.2x + 0.6
To clear parentheses and align terms using decimals.
2
Combine constants on the left side
1.2x3.8=0.2x+0.61.2x - 3.8 = 0.2x + 0.6
To simplify the left-hand side of the linear equation.
3
Isolate the variable xx
x=4.4x = 4.4
To determine the value of the unknown variable.
4
Evaluate the target expression
2020
To compute the final value of the expression 5x25x - 2.

Key Concept

Solving linear equations with fractional and decimal coefficients
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