Answer:
$45.22
Step-by-step explanation:
The number of miles per gallon can be represented by the ratio:

Since we know the unit rate of 26 miles per gallon of gas, we can set up a proportion, or equivalent ratios, to find the number of gallons needed for 420 miles:
, where 'x' is the number of gallons of gas
cross-multiply and divide: 26x = 420 or x ≈ 16.15 gallons
If gas is $2.80 per gallon, take the total number of gallons needed and multiply by $2.80:
16.15 x $2.80 = $45.22
<span>%Antifreeze=<span><span>V<span>Antifreeze</span></span><span>V<span>Fluid</span></span></span></span>
<span><span>V<span>Fluid</span></span>=<span><span>V<span>Antifreeze</span></span><span>%Antifreeze</span></span></span>
<span><span>V<span>Antifreeze</span></span>=<span>V<span>fluid</span></span>∗%Antifreeze</span>
I want to find the amount of antifreeze in a 15 quart solution with 30% antifreeze
<span><span>V<span>Antifreeze</span></span>=15∗0.30</span> =18/4 quarts of antifreeze
Similarly, I want to find the amount of antifreeze in a 15 quart solution with 35% antifreeze first.
<span><span>V<span>Antifreeze</span></span>=15∗0.35</span> = 21/4 quarts of antifreeze
<span>the difference between 21/4 and 18/4 is 3/4 quarts, which is the amount of pure antifreeze I've added in.
</span><span>
SO the V_fluid I replaced with 3/4 quarts of antifreeze is (3/4)/ 0.35</span>