Question

$ 45= 3 books 3 Pens
$ 177= 11 Books 12 Pens

Cost of b=
P=

Answer 1

3 p + 3b = 45
11 b + 12 p = 177

12 b + 12 p = 180

Subtract the second equation from the third.

b = 3.

9 + 12 p = 177
12 p = 168

p = ?

Answer 2

I made a mistake near the end.

3p + 9 = 45
3p = 36
p = 12