What do I need to find?
Your answer is correct.
What information do I need to use?
100% = 240 miles, she has already driven 15% of 240, so she has driven x miles.
How will I use the information?
Set up a proportion. If she has already driven 15% out of 100% of the distance, then you should write [tex]\frac{15}{100}[/tex] for the first fraction. This is proportional to [tex]\frac{x(miles)}{240(miles)}[/tex]. This means that [tex]\frac{15}{100} = \frac{x}{240}[/tex]. Wait, but this is confusing. How on Earth do we solve it? Let's take a closer look. If [tex]\frac{x}{240}[/tex] is supposed to equal 15/100, then this means that x/240 divided by 15/100 should give us the answer. So, even though it looks complicated, all you have to do is cross multiply like this:
[tex]\frac{15}{100} = \frac{x}{240} --> 240 * 15 = 100x --> 3600 = 100x[/tex]
Now isolate x:
[tex]\frac{3600}{100} = \frac{100x}{100}[/tex]
So x = 36, which means she has already driven 36 out of 240 miles. Lucia still has to drive 204 miles to reach her destination.
1.) In this case, 56 = 100% and 25% of the sandwiches were tuna. This means that 75% of the sandwiches were not. If [tex]\frac{25}{100} = \frac{x}{56}[/tex] and you use the same method above, x is equal to 14. If 14 is 25% then that means the other 75% = 14 * 3. So 42 sandwiches were not tuna.
2.) [tex]\frac{60}{100} = \frac{x}{450}[/tex]
--> [tex]27000 = 100x[/tex]
---> [tex]\frac{27000}{100} = \frac{100x}{100}[/tex]
He still has $270 left to pay.
