Solving word problems using linear system

Question

If a pen and 26 pencils cost $40, while five pens and 3 (26) pencils cost $130, how much is each pen and pencil?

Answer 1

cost of one pen = x

cost of one pencil = y

x + 26y = $ 40

5x + 3(26)y = $130 one pen cost = $ 5

one pencil cost = $ 1.35.

substitute method

26y = 40 - x

5x + 3(40 -x) = 130

5x + 120 - 3x = 130

2x = 130 - 120

x = $ 5 cost of one pen

5 + 26y = 40

y = 35/26 = $ 1. 35 cost of one pencil