<span>One pair of metric unit of length would be meters and kilometers. 1 km is equal to 1000 meters. Metric system is the official/standard in measuring length, mass, area, volume, speed, etc. and it is the agreed system of measurement.</span>
Answer:
a. b=4
Step-by-step explanation:

From the attached triangle drawn below:
NL=20, LM=3b, 

Since we are told that:

The correct option is A.
She received 12 calls from her son and 30 calls in total.
40% of 30 is 12.
Step-by-step explanation:
multiple possibilities.
e.g.
we could use Pythagoras to get QR, and then use the law of sine to get angle P.
or we can use the law of sine to get angle R, and then use the rule that the sum of all angles in a triangle is always 180° to get angle P.
I propose the second option :
the law of sine :
a/sin(A) = b/sin(B) = c/sin(C)
with a, b, c being the sides always opposite of their associated angles.
33.8/sin(R) = 57.6/sin(90) = 57.6
sin(R) = 33.8/57.6 = 0.586805555...
R = 35.93064691...°
180 = 90 + 35.93064691... + P
P = 54.06935309...°