270 algebra De mystif ieD
- 0% 50% 40%
cups
+ 25 – x^
cups
=^25
cups
0 x + 0.50(25 – x) = 0.40(25)
00 50 25 04025
01 25 05 0100
12512
xx
x
+−=
+− =
−−
.( ).()
...
. ..
..
.
.
5
05025
25
050
5
−=−
=−
−
=
x
x
x
Mix 5 cups of decaffeinated coffee with 25 – x = 25 – 5 = 20 cups of 50%
caffeine coffee to produce 25 cups of 40% caffeine coffee.
- 100% 35% 50%
x^
ounces
+^18
ounces
= x + 18^
ounces
1.00x + 0.35(18) = 0.50(x + 18)
1000 35 18 05018
10063050 9
050
..().( )
...
.
xx
xx
+=+
+= +
− xxx
x
x
x
−
+=
−−
=
=
050
0506390
63 63
05027
27
050
.
...
..
..
.
.
xx=54.
Add 5.4 ounces of pure acid to 18 ounces of 35% acid solution to pro-
duce a 50% acid solution.