The answer is 8.
half of 16 is 8
Step-by-step explanation:
2×length + 2×width = 45
length = 4×width
now, we are using the second equation (a variable identity) in the first equation
2×4×width + 2×width = 45
8×width + 2×width = 45
10×width = 45
width = 45/10 = 4.5 in
length = 4×width = 4×4.5 = 18 in
the area of the rectangle is
length × width = 18 × 4.5 = 81 in²
Let f and e represent the amount of 40% and 80% solutions used...
We are told the f+e=20 which means that f=20-e and we can say that:
(.4f+.8e)/20=.7, using f=20-e in this equation we see that:
.4(20-e)+.8e=14
8-.4e+.8e=14
8+.4e=14
.4e=6
e=15, and since f=20-e then
f=5
So 15 quarts of 80% solution is mixed with 5 quarts of 40% solution to produce a 20 quart mixture of 70% solution.