Alady buys 20 trinkets at a yard sale.
the cost of each trinket is either $0.30
or $0.65. if she spends $8.80, how
many of each type of trinket does she
buy?

lady buy 12 trinkets for $0.30 each and 8 trinkets for $0.65 each.

Step-by-step explanation:

Given data:

Total number of trinkets = 20

Cost per trinket may be either $0.30 or $0.65.

Assume total number of trinkets as x when she purchased for $0.30

and y  when she purchased for $0.65

Then we have following equation

x + y = 20 (1)

Total amount of money spent = $8.80

Then the equation will be

0.30x + 0.65y = 8.80 (2)

from equation we have x = (20 - y), use this in equation 2, we have

0.30(20 - y) + 0.65y = 8.80

6 - 0.30y + 0.65y = 8.80

0.35y + 6 = 8.80

0.35y = 8.80 - 6

0.35y = 2.80

y = 8

we have x value

x = 12

Therefore, lady buy 12 trinkets for $0.30 each and 8 trinkets for $0.65 each.

f(x) has value 150 at x= 0

and 0 at x= 3

so d(f(x))/dt = slope = -150/3 = -50