Hi can someone help me.can't get the answer.you need to find a+b+c+d

The sum of the product of 4 and x and the product of 7 and y is 61. the sum of the product of 12 and x and the product of 21 and y is 61. what are the values of x and y?

The american academy of pediatrics wants to conduct a survey of recently graduated family practitioners to assess why they did not choose pediatrics for their specialization. provide a definition of the population, suggest a sampling frame, and indicate the appropriate sampling unit.

Astore ordered 750 candles a total wholesale cost of $7910.20. the soy candles cosy $12.17 each and thespecialty candles cost $9.58each. how many of each were bought?