Question

A mail clerk found that the total weight of 155 packages was 815 pounds. if each of the packages weighed either 3 pounds or 8 pounds, how many of the packages weighed 8 pounds?

Answer 1

70 packages of 8 pounds each

Explanation:

A mail clerk found that the total weight of 155 packages was 815 pounds.

If each of the packages weighed either 3 pounds or 8 pounds.

Let x number of package of 3 pounds and y number of packages of 8 pounds

Total number of packages are 155

Thus, x + y = 155 ------- ------(1)

Total weight of 3 pound package = 3x

Total weight of 8 pound package = 8y

Total weight of 155 packages = 815

Thus, 3x + 8y = 815 -----------(2)

Solving equation 1 and equation 2

Multiply first equation by -3

-3x - 3y = -465

3x + 8y = 815

5y = 350

y = 70

Hence, The number of packages of weighted 8 pounds are 70

Answer 2

For this on you need to set up two equations
x + y = 155 total number of packages
3x+8y=815 total weight
Then multiply both sides of the first equation by 3: 3x +3y = 465
Then combine the two equations by subtracting the first one from the second one which gets you 5y=350 so y = 70 so we have 70 packages weighting 8 pounds.