Answer:
95°
Step-by-step explanation:
You want the measure of angle TVZ, when adjacent angle (2x+5)° and its supplement (2x+15)° are given. The larger of these is a vertical angle with respect to TVZ.
Linear pair
The angles marked (2x+15)° and (2x+5)° are a linear pair, hence supplementary.
((2x+15)° +(2x+5)° = 180°
4x +20 = 180 . . . . simplify
x +5 = 45 . . . . . . . divide by 4
x = 40 . . . . . subtract 5
Angle TVZ is a vertical angle with respect to the one marked (2x+15)°, so has the same measure:
∠TVZ = (2(40)+15)°
∠TVZ = 95°
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Alternate solution
The two angles RVW (2x+15)° and ZVW (2x+5)° obviously differ by 10°. They are a linear pair, so their sum is 180°. Finding these angles is then a "sum and difference" problem. The larger of the solutions is the one we want, as (2x+15)° is a vertical angle to TVZ. We know the larger of the solutions to the sum and difference problem will be (180° +10°)/2 = 95°, the measure of TVZ.
More about sum and difference problems:
When a+b = s, and a-b = d, the larger value (a) can be found by adding these equations: (a+b) +(a-b) = s+d, or 2a = s+d, or a = (s+d)/2. This is the expression we used above to find the larger of the two angles. (You notice it is not necessary to solve for x.)
