Answer:
12 which is on C
Step-by-step explanation:
use pathogoras theorem
a^2+b^2=c^2
16^2+b^2=20^2
256+b^2=400
b^2=400-256
b^2=144
b= square root of 144
b= 12
Standard form: -3x +5y= -1
You multiply 10 12 times and you will have 1000000000000
than multiply it again by 4.18549 and you will get 418549000000
The most important thing that you have to know is that all angles in a triangle equals 180°