Answer:
80
Step-by-step explanation:
every triangle adds up to 180 sort of, in this case, turn 4 into 40. 40+20=60 so add 80 to be 180!!!
5/(3+i)* 3-i/3-i= 15-5i/9-1= 15-5i/8
Yes, that like will divide the side in proportion
There is no variables here
You need a common denominator while subtracting because really a fraction is a division problem and you cannot do 4/5-8/9 it does not make sense as for multiplication you really just multiplying everything that is why it makes sense.
