So the equation looks like this : 15*3x=78
subtract 15 from both sides: -15 -15
then divide by 3 from both sides
to isolate the variable: 3x=63
3/3x=63/3
x=21 (your mystery number is 21)
The answer would be 53. This can be found by add 127 twice (xy and uz) and subtracting it from 360. This would give you 106 and you would divide it by 2 for the 2 angles left and get the answer.
It is C. r=6
3 * 6 = 18 + 2 =20
Um..same, whats your favorite