The efficient combination of outputs is produced when the marginal rate of transformation between the two goods(which measures the cost of producing one good relative to the other)is equal to the consumer's marginal rate of substitution (which measures the marginal benefit of consuming one good relative to the other). The efficient combination of outputs is produced when the marginal rate of transformation between the two goods (which measures the cost of producing one good relative to the other) is equal to the consumer's marginal rate of substitution (which measures the marginal benefit of consuming one good relative to the other)