Answer:
96 degrees
Step-by-step explanation:
you have two angles that each measure 42 degrees, giving you 84 degrees combined
there are 180 degrees in a triangle, therefore the vertex angle is equal to 180 minus 84, or 96 degrees
check:
42 + 42 + 96 = 180
180 = 180
It is 0 because of the sin being 0
Answer:
A) 
B) T = -5 °C
Step-by-step explanation:
A) Let T be the change in temperature of the week. T is determined as the total temperature change (-20°C) divided by the number of weeks that have passed (4 weeks). The expression is:

B) In order to simplify the expression, simply perform the division.

This means that the temperature has dropped by 5 degrees each week.
360 degrees is a full turn, so if you multiply 30 degreed by 12, you go around in a circle.
I feel like there is something missing from this question, for example how large is the tree house? If these are just plain measurements, then I would opt for B.