to find no. of swans

Let N be the total numbe of swans,

Swans at shore + Swans in water, swimming = Total number of swans.

7N /2 + 2 = N

7N /2  = N - 2

Sqaring both sides,

49N/4 = N² -4N + 4

49N = 4N² -16N + 16

4N² - 65N + 16 = 0

N = [65±(65²-4x16x4)]/8 = [65±63]/8 = 128/8 = 16.

Total number of swans are 16.

Regards,

Team,

TopperLearning.