Soo-Jin and Mary had equal number of mermaids. After soo-Jim gave 54 mermaids to Mary,mary had 7 times as many mermaid as soo-Jin.

Answer 1

M=J

M+54=7(J-54) = J+54

7J-378 = J+54

6J = 432

J = 72

Both originally had 72

After giving Mary 54, he had 72-54=18

and Mary now has 72+54=126 which is 7 x 18