You bought an antique porcelain doll for $15 at an estate sale. you get it appraised and you are told that the doll is woth $150 .what was the percent increase

The anwser cause i do not understand just plez

Asquare and an equilateral triangle have the same perimeter. each side the triangle is 4 inches longer than each side of the square. what is the perimeter of the square

I’m still confused on how to work the percentages