Solve for a.
p + a + r = k

Step-by-step explanation:

sqrt(p+a)=k-r

we raised to the power of 2 both sides

(p+a)=k^2-2kr+r^2

a=k^2+r^2-2kr-p

choice 2

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