concerning sequences!

Let a, b be the two numbers

For (a),

a + b = 2p .......................... (1)

√ab = q
ab = q^2
a = q^2 / b .......................... (2)

Put (2) into (1),
q^2 / b + b = 2p
q^2 + b^2 = 2bp
b^2 - 2bp + q^2 = 0

b = [ p +/- √(4p^2 - 4q^2) ] / 2 = p +/- √(p^2 - q^2)

Note that a and b are symmetric, hence the answer.

For (b), simply put p=30 and q=18 into the answer of (a).