find y for 2x-4=8 and 5x+y=20

1) You have the following 2 equations:

[1]:

2 x - 4 = 8

[2]:

5 x + y = 20

2) Solving for x:

2 x - 4 = 8

[1]

ⓘ We add

4

to both sides

2 x = 8 + 4

ⓘ Start from

8

and move forward

4

on the number line:

8 + 4

12

2 x = 12

ⓘ Both sides are divided by

2

x = \frac{12}{2}

ⓘ We simplify the fraction by dividing the numerator and the denominator by

2

, their greatest common divisor:

\frac{12}{2}

6

Solution obtained [1]:

x = 6

3) Solving for y:

5 x + y = 20

[2] using

x = 6

ⓘ Perform multiplications before additions and subtractions:

5 \cdot 6

30

30 + y = 20

ⓘ We subtract

30

from both sides

y = 20 - 30

ⓘ Start from

20

and move back

30

on the number line, going below zero:

20 - 30

-10

Solution obtained [2]:

y = -10

▶Solution:

{x = 6, y = -10}

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