Algebra P6

If p is directly proportional to the square root of q.The sum of p when q=49 and q=784 is 10.
This may not be a P6 Question as square root is not cover in Primary School.

p ^ 2 =  c ^ 2 x q

p1 x p1 = c x c x 49
             = c x c x 7 x 7
p1 = 7c

p2 x p2 = c x c x 784
            = c x c x 28 x 28
p2 = 28c

p1 + p2 = 7c + 28c
             = 35c

35c = 10

c = 10 ÷ 35 = 2/7

p ^ 2 = 2/7 x 2/7 x q

If q = 196, p x p = 2/7 x 2/7 x 196
                          = 4 x 4
                  p = 4