Question 144560
.15x+.18(90-x)=.159*90
.15x+16.2-.18x=14.31
-.03x=14.31-16.2
-.03x=-1.89
x=-1.89/-.03
x=63 oz. of 155 copper is needed.
90-63=27 oz. of 18% copper is needed.
proof:
.15*63+.18*27=14.31
9.45+4.86=14.31
14.31=14.31