A local coffee shop sells two types of coffee blends: House Blend and Dark Roast. The House Blend costs $8 per pound, and the Dark Roast costs $12 per pound. A customer wants to buy a mixture of the two blends totaling 5 pounds, spending exactly $50. Which equation represents this situation, where (x) is the number of pounds of House Blend and (y) is the number of pounds of Dark Roast?