Question

once upon a time miss abc invited 50 enemies to dinner. solve this question

Answer 1

Miss ABC can use 0.5 pounds of poison maximum.

Let the mass of X be $x$ pounds, then mass of Y is $y=0.5-x$ pounds.

The price should be minimised, and the effect should be 50 people killing.

$$75x+200(0.5-x)=50$$

$$75x+100-200x=50$$

$$125x=50$$

$$x=\dfrac{50}{125}$$

$$x=0.4$$

Then

$$y=0.5-0.4=0.1$$

The total price will be 

$$0.4(100)+0.1(400)=80(gold\ pieces)$$

0.4 pounds X, 0.1 pounds Y, 80 gold pieces.