Question

Solve for x in the diagram below.
(2x + 30°
40°
40°
т

Answer 1

x=35

Explanation:

The 3 angles are on a straight line. A straight line is equal to 180 degrees. Therefore, the 3 angles are supplementary and add to 180 degrees.

40+2x+30+40=180

Combine like terms. Add all the terms on the left side without a variable.

2x+(40+30+40)=180

2x+110=180

We want to find out what n is. In order to do this, we have to get n by itself. Perform the opposite of what is being done to the equation. Keep in mind, everything done to one side, has to be done to the other.

110 is being added to 2x. The opposite of addition is subtraction. Subtract 110 from both sides.

2x+110=180-110

2x=180-110

2x=70

x is being multiplied by 2. The opposite of multiplication is division. Divide both sides by 2.

2x/2=70/2

x=70/2

x=35

Answer 2

x = 35°

Explanation:

assuming that the straight line at the bottom of the figure is actually a straight line, that means all the angles along that straight line must add up to 180 °

i.e.

40 + (2x+30) + 40 = 180

40 + 2x+30 + 40 = 180

110 + 2x = 180 (subtract 110 from both sides)

2x = 180 - 110

2x = 70

x = 35