Question 993223
35+40= 75 Total of all silver alloy
35/75= 46.7% of the total silver alloy is 80% silver alloy
40/75= 53.3% of the total silver alloy is 25% silver alloy

(0.467 x 0.8)+(0.533 x 0.25)= 0.374+0.133= 0.507= 50.7% is the percentage concentration of the resulting alloy.