Let t and s represent the masses of 20% and 60% alloys respectively.
t+s=80, s=80-t
(0.2t+0.6s)/80=0.52 multiply both sides by 80
0.2t+0.6s=41.6, now using s=80-t in this equation gives us:
0.2t+0.6(80-t)=41.6 perform indicated multiplication on left side
0.2t+48-0.6t=41.6 combine like terms on left side
-0.4t+48=41.6 subtract 48 from both sides
-0.4t=-6.4 divide both sides by -0.4
t=16, since s=80-t
s=64
So 16kg of 20% alloy is mixed with 64kg of 60% allow to make 80kg of a 52% alloy.
