Write a doubles fact you can use to find the sum of 6+7

We could use 7+7=14 to find the sum of 6+7.

Explanation:
7+7=14 is one of the two closest doubles to 6+7.
We know that:
7 is 1 more than 6; this means:
7+7 will be 1 more than 6+7.
7+7=14, so finding 1 less,
6+7=13.

Answer d; a supplementary angle = 180°, so if that angle = 150°, y would = 30°.