Question 1101216
We know the total amount is 1700 g 
We know the percentage of the total amount is 44%
We know the total amount has 748 g of 100%
We want to know the amount of copper at 41%
We want to know the amount of copper at 51%
x+y=1700,
0.41*x+0.51*y=0.44*1700
0.41*x+0.51*y=748
x=1700-y
0.41*(1700-y)+0.51*y=748
697-0.41y+0.51*y=748
0.1*y=51
We now know amount of copper at 51%
y=510 g at 51%
x=1700-y
We now know amount of copper at 41%
x=1190 g at 41%
check
0.41*1190+0.51*510=0.44*1700
487.9+260.1=748
748=748
ok