Lets call x the amount of 18% solution and y the amount of 40% solution, and write as equations the info of the problem:
18x + 40y = 10(20)
x + y = 10
lets multiply the second equation by -18 and add to the first:
18x + 40y = 200
-18x -<span> 18y = -180
</span>----------------------
0 + 22y = 20
y = 20/22 = 10/11
and substitute in the original equation:
x <span>+ y = 10
</span>x = 10 - y
x = 10 - 10/11
x = 110/11 - 10/11
x = 100/11
so they have to use 100/11 liters of 18% solution and 10/11 liters of 40% solution
Answer: 
Step-by-step explanation:

Write as slope-intercept form y = mx + b, where m is the slope and b is the y-intercept.


Therefore, the slope is
.
Answer:
D.) 9*pi >27
Step-by-step explanation:
9*pi = 28.2743338823...
28.2743338823... > 27
D.) 9*pi > 27 = True
Regards!
6/7 × 4 would be the correct answer. This is because 6/7 × 4= 3 3/7 which is equal to 4/7 × 6= 3 3/7. No other expression would equal 4/7 × 6