step 1
Find out the measure of angle B
Remember that
The sum of the interior angles in any triangle must be equal to 180 degrees
so
A+B+C=180 degrees
substitute given values
45+B+100=180
B=180-145
B=35 degrees
step 2
Find out the length of the side a
Applying the law of sines
substitute given values
a=2.15 units
step 3
Find out the length of the side b
applying the law of sines
substitute given values
b=1.75 units