Issac shovels driveways to earn money. He can shovel 14 driveways in 8 hours. Earns $25.00 for each driveway. Issac is saving up to buy a new computer that costs $831.25. How many hours does Issac need to work to earn enough money to purchase the computer?

Step 1 find the number of driveways to shovel

25x = $831.25

x = $831.25/25

= 33.25 driveways

Step 2

He can shovel

14 driveways = 8 hours

33.25 driveways = x

Cross Multiply

14x = 8 × 33.25

x = 8 × 33.25/14

x = 19 hours

6 0

3 years ago

Two certificates of deposit pay interest at rates that differ by 4%. Money invested for one year in the first CD earns $175 inte

wolverine [178]

We are told that the principle is the same for both investments so we can say:

315=P(r+4)/100 and 175=Pr/100 solving both for P you have:

P=31500/(r+4) and P=17500/r since P=P:

17500/r=31500/(r+4)

175(r+4)=315r

175r+700=315r

-140r+700=0

-140r=-700

r=5

So the rates are 5% and (5+4)=9%

check...

P(9/100)=315 and P(5/100)=175

P=31500/9 and P=17500/5

P=157500/45 and P=157500/45

So P=P

note: P=$3500

3500(9/100)=$315

3500(5/100)=$175

5 0

3 years ago