Question

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?

Answer 1

The cost of one puzzle is $15

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