1. Let’s denote the degree measure of the angle A through x.
2. Determine the degree measure of the angle B:
3 * x = 3x.
3. Let’s compose and solve the equation:
3x + x = 180˚;
4x = 180˚;
x = 180˚: 4;
x = 45˚.
4. The degree measure of the angle A is equal to 45˚.
5. What is the degree measure of angle B?
3 * 45˚ = 135˚.
6. What is the angle D equal to?
Since angle B is equal to angle D, then the degree measure of angle D is 135˚.
Answer: angle D is 135˚.
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