Answer: option d. the argument is valid by the law of detachment.
The law of detachment consists in make a conlcusion in this way:
Premise 1) a => b
Premise 2) a is true
Conclusion: Then, b is true
Note: the order of the premises 1 and 2 does not modifiy the argument.
IN this case:
Premise 1) angle > 90 => obtuse
Premise 2) angle = 102 [i.e. it is true that angle > 90]]
Conclusion: it is true that angle is obtuse
Make x=0 in the second equation, giving you y=-3. If you plug that in to the top equation you would get x-3(-3)=-19, x+9=-19,x=-28.
Option C:

Solution:
Sample space for two dice

Number of sample space = 36
Pair getting sum of 12 = (6, 6)
Number of pair getting sum of 12 = 1
Pair getting doublet = (1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)
Number of pair getting doublet = 6
Total number of pair getting sum of 12 or doublet = 1 + 6 = 7
Probability of getting sum of 12 or doublet


Hence,
is the probability of getting a sum of 12 or doublet when rolling a pair of dice.