Answer:
18
Step-by-step explanation:
30*0.4=12
This means 40% of 30 is 12 and Ana has completed 12 problems.
30-12 = 18, so she still needs to do 18 problems.
4 is the gif of 20, 12, and 8
7.5% is 3/40. The equation is y=15250(1-3/40)ˣ=15250(37/40)ˣ.
When x=8 this becomes $8173.42.
First off, let's convert the percentages to decimal format, so our 77% turns to 77/100 or 0.77, and our 55% turns to 55/100 or 0.55 and so on
now, the sum of both salines, must add up to the 77% mixture, let's say is "y"
so, 11 + 4 = y, and whatever the concentration level is, must also sum up to the mixture's concentration of 77%
anyway thus

solve for "x"
X=117 degrees
Y = 63 degrees
Z = 117 degrees