Esther purchased two rock tumblers and one spy pen for $74. eli purchased two puzzles and a spy pen for $50. sabine purchased a rock tumbler and two puzzles for $57. based on this, how much does one puzzle cost?

The cost of one puzzle is $15

Step-by-step explanation:

Let

x > the cost of one rock tumbler

y > the cost of one spy pen

z > the cost of one puzzle

we know that

2x+y=74 > equation A

2z+y=50 > equation B

x+2z=57 > equation C

Subtract equation B from equation A

2x-2z=74-50 > 2x-2z=24 > equation D

Adds equation C and equation D

x+2z=57

2x-2z=24

2x+x=57+24

3x=81

x=$27

Find the value of z

x+2z=57

27+2z=57

2z=57-27

2z=30

z=$15