8 pounds
You can find the percent of ingredient A in the detergent by dividing the amount of A in the ratio (1), by the total amount in the ratio (1 + 4 + 5, which gives you ten). This gets you 1/10, which is 10% of the detergent. Since you have 80 pounds, 10% of it would be 8 pounds, but you could just multiply 80 by the fraction you got (1/10) to get 8 pounds too.
