Question

Two cans of paint and 1 brush cost $37. Four cans of paint and 3 brushes cost $81. Find the cost of one can of paint.

Answer 1

2c + b = 37 ....multiply by -3
4c + 3b = 81
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-6c - 3b = - 111 (result of multiplying by -3)
4c + 3b = 81
------------------add
-2c = - 30
c = -30/-2
c = 15 <== $ 15 for a can of paint

and it costs $ 7 for each brush