Question

20x-(5x-6y), если 5x+2y=5,4

Answer 1

$20x - (5x - 6y) = 20x - 5x + 6y = 15x + 6y = 3(5x + 2y) = 3 \times 5.4 = 16.2$

Answer 2

To find the value of the expression 20x - (5x - 6y) when 5x + 2y = 5.4, we first need to solve the system of equations:

1. 20x - (5x - 6y) = ?
2. 5x + 2y = 5.4

Let's proceed with the solution:

Step 1: Solve the second equation for one of the variables. Let's solve for y:

5x + 2y = 5.4

Subtract 5x from both sides:

2y = 5.4 - 5x

Divide both sides by 2:

y = (5.4 - 5x) / 2

Step 2: Substitute the value of y from the second equation into the first equation:

20x - (5x - 6y) = 20x - 5x + 6((5.4 - 5x) / 2)

Step 3: Simplify the expression:

20x - (5x - 6y) = 20x - 5x + 6(5.4/2 - 5x/2)

20x - (5x - 6y) = 20x - 5x + 3(5.4 - 5x)

20x - (5x - 6y) = 20x - 5x + 16.2 - 15x

Step 4: Combine like terms:

20x - (5x - 6y) = 20x - 5x - 15x + 16.2

20x - (5x - 6y) = (20x - 5x - 15x) + 16.2

20x - (5x - 6y) = 0x + 16.2

Step 5: Finally, simplify the expression:

20x - (5x - 6y) = 16.2

So, the value of the expression 20x - (5x - 6y) is 16.2 when 5x + 2y = 5.4.