algEBRA word problem
posted by marko on .
1 julies car travels 27 miles per gallon of gassoline used. she recently travedled 324 miles. how many gallons of gasoline did her car use? im learning about algebra multiplicaion property of equality and divsion property of equality
would i write: i know i have to divide 324 / 27 = 12
but im not sure how to write out for algebra using a variable.
g/27 = 324
27 *g/27 = 324/27
g= 12 gallons. is that right?
2) a local park rents paddle boats for $5.50 per hour. you have $22.00 to spend. How many hours can you rent a boat? 22.00 / 5.50 is : 4 hrs
do i write it as:
h/5.50 = 22.00
5.50 * h/5.50 = 22.00 / 5.50
h = 4
is that right?
3) a video store charges $2.75 per day for overdue videos. You owe a late fee of $13.75. How many days overdue is the video?
i wrote: v/2.75 = 13.75
2.75 * v/2.75 = 13.75/2.75
v= 5 days late.
is this ok?
If you're confused over what to divide or multiply, keep the units with the numbers. As you work, try to cancel out the units you don't want.
For example, in the first problem, you have a consumption rate: 27mi/1gal
That fraction is essentially 1. Every 27 miles equals 1 gallon.
You also have 324 mi
You want to convert miles to gallons
You can always multiply by 1 without changing anything:
324mi * 1gal/27mi = 324/27 gal
See how the miles cancel out, leaving just the gallons?
Now you got the right answer, but look at your equation:
g/27 = 324
If you work that out, you get g=27*324
What you need is g * 27 = 324
That is, the number of gallons * the miles/gallon yields the miles traveled. You know this value, but had trouble with the equation. Take a look. On the left you multiplied by 27, but on the right you divided by 27. To manipulate an equation, you need to do the same thing to both sides.
local park rents paddle boats for $5.50 per hour. you have $22.00 to spend. How many hours can you rent a boat?