Question 526733
Alloy one
=========
Amount = x grams
Silver = 70% = 0.7
Alloy two
=========
Amount = 400-x grams
Silver = 40% = 0.4
Mixture Alloy
============
Amount = 400 grams
Silver = 61% = 0.61


(Amount of Alloy one)*sliver + (Amount of Alloy two)*sliver = (Amount of Mixture Alloy)*sliver 

(x)(0.7)+(400-x)(0.4)=400*0.61
0.7x+160-0.4x=244
0.7x-0.4x=244-160
0.3x=84
0.3x/0.3=84/0.3
x=280


Alloy one
=========
Amount = x = 280 grams
Silver = 70% = 0.7
Alloy two
=========
Amount = 400-x - 400-280 = 120 grams
Silver = 40% = 0.4
Mixture Alloy
============
Amount = 400 grams
Silver = 61% = 0.61


120grams ______40% alloy
280grams___  g 70% alloy