I need to know how to solve this and the answer

69°

Step-by-step explanation:

180 - 21 -90 = 69

hope this helps...

The missing angle is 69°

Step-by-step explanation: When all the angles have their vertex on a straight line, they must add up to 180° They are "supplementary" angles.

The "box" in the corner of an angle is a symbol for "right angle" so that is a way to have a "given" 90°

Knowing that, you can add the "given" 90° + 21° to get 111°

Subtract 111° from 180° to find Angle a:

180 - 111 = 69

d, x=8

step-by-step explanation:

simplifying

4x + -5 = 2x + 11

reorder the terms:

-5 + 4x = 2x + 11

reorder the terms:

-5 + 4x = 11 + 2x

solving

-5 + 4x = 11 + 2x

solving for variable 'x'.

move all terms containing x to the left, all other terms to the right.

add '-2x' to each side of the equation.

-5 + 4x + -2x = 11 + 2x + -2x

combine like terms: 4x + -2x = 2x

-5 + 2x = 11 + 2x + -2x

combine like terms: 2x + -2x = 0

-5 + 2x = 11 + 0

-5 + 2x = 11

add '5' to each side of the equation.

-5 + 5 + 2x = 11 + 5

combine like terms: -5 + 5 = 0

0 + 2x = 11 + 5

2x = 11 + 5

combine like terms: 11 + 5 = 16

2x = 16

divide each side by '2'.