help please with this problem?

Question

Nancy and Adriana use a metal alloy that is 16% copper to make jewelry. How many ounces of
an 11% alloy must be mixe
d with a 24% alloy to form 130
ounces of the desired alloy?

Answer 1

e=number of ounces of 11%Cu, t=number of ounces of 24% Cu

     e+    t=130                 total weight of alloy

.11e+.24t=.16×130=20.8 total weight of Cu

Rewrite as

    e+   t=130

11e+24t=2080

multiply first equation by 11

11e+11t=1430

11e+24t=2080

subtract

13t=650 and so t=50,. which makes e=80