Step-by-step explanation:
A=s*s
A=s^2
52=s^2
s=√52
s=7.2 one side of the square
s*4 to get the four sides
7.2*4=28.8 cm length of the first piece
40-28.8=11.2cm length of the second piece
$15 more, than twice Friday's earnings
d is how much he earned on Friday
s is how much he earned on Saturday
2d + 15 = s