Answer:
$2.25
Step-by-step explanation:
Let "b" be the price of 1 brownie and "c" the price of 1 cookie.
At a bake sale, a student spent $11.00 buying 3 brownies and 5 cookies. Symbolicaly,
3 b + 5 c = 11.00 [1]
His friend spent $3.95 buying 1 brownie and 2 cookies. Symbolicaly,
1 b + 2 c = 3.95
b = 3.95 - 2c [2]
If we replace [2] in [1], we get
3 (3.95 - 2c) + 5 c = 11.00
11.85 - 6c + 5c = 11.00
c = 0.85
If we replace c = 0.85 in [2], we get
b = 3.95 - 2 (0.85) = 2.25
Solution :
Let A = Economics, B = Mathematics
n(A) = 311, n(B) = 243, 
a). So, 
= 311 + 243 - 135
= 419
b). n(A only) = 311 - 135
= 176
n(B only) = 243 - 135
= 108
Exactly one of these two courses
= 0.568
c). Neither economics nor mathematics
= 0.162
I think first 80 and second 90
Answer:
10635
Step-by-step explanation:
Honestly, I dunno. I just added it.
