5y + (86 - y) = 86 + 4y

All real values, (-∞, ∞)

Step-by-step explanation:

Step 1:  Distribute

5y + (86 - y) = 86 + 4y

5y + 86 - y = 86 + 4y

Step 2:  Combine like terms

5y + 86 - y = 86 + 4y

4y + 86 = 86 + 4y

Step 3:  Subtract 4y from both sides

4y + 86 - 4y = 86 + 4y - 4y

86 = 86

Step 4:  Subtract 86 from both sides

0 = 0

 All real values, (-∞, ∞)

0

Step-by-step explanation:

Given

5y + (86 - y) = 86 + 4y

Open parenthesis

5y + 86 - y = 86 + 4y

Rearrange the expression

5y - y + 86 = 86 + 4y

4y + 86 = 86 + 4y

Combine like terms

4y - 4y = 86 - 86

0 = 0

0

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.

step-by-step explanation: