Question 661942
p = pb cookies dozen
y = ch cookies dozen
p = y + 85
6.5p + 9y = 4055.5 
Substitute p
6.5(y+85) + 9y = 4055.5
Distribute and solve for y
6.5y + 552.5 + 9y = 4055.5
15.5y = 4055.5 - 552.5
15.5y = 3503
y = 226
p = 226 + 85 = 311 dozen pb cookies