How did they get this answer? please help!

The formula for calculating speed is:

S (speed) = D (distance) *divided by* T (time)

or just simply without labels:

S=D/T

In the problem u'r doing 9/4 (hope i see it correct) represents D, 1/2 represents T, and 4.5 represents S

Hope this helps)

the sum of all the angles in a triangle are equal to 180

so you can add   the 3 given angles together to equal 180:

5y + 2y + 2y = 180

or since all three angles have the same letter, combine the 3 angles to equal 180:

9y = 180