Question

HELP QUICK PLEASE!!!

Answer 1

Answer:

$b=19\ ounces$

Step-by-step explanation:

System Of Equations

We know the scale shows a false reading for the weights by a constant value. Let's call e the weight it adds or subtracts from the real weight it measures.  

When the box is put on the scale, the real weight is b, but the scale shows

$b+e=15$

When the bag is weighted, the real value is g, but the scale shows

$g+e=12$

Finally, when both are measures, the real weight is b+g and the scale shows

$b+g+e=31$

We have formed a system of equations. It's easy to find the value of b, we just need to subtract the last two equations

$b+g+e-g-e=31-12$

$\boxed{b=19\ ounces}$