# Math Help - Revision

1. ## Revision

Hey, just needing some help here:

How much simple interest would be paid on a $700 loan for 5 years (60 months i think, it's easier if you convert to months) at a rate of interest 18%: [my workings: prt= 700x18x60/100 is that right?] how would i do it? and also Sarah sold her bike for$300 which is 80% of the amount she originally paid for it. What did she pay originally for it?

2. Originally Posted by Sazza
Hey, just needing some help here:

How much simple interest would be paid on a $700 loan for 5 years (60 months i think, it's easier if you convert to months) at a rate of interest 18%: [my workings: prt= 700x18x60/100 is that right?] how would i do it? use years as the time. Simple interest = PRT = 700 x 0.18 x 5 = 630 Sarah sold her bike for$300 which is 80% of the amount she originally paid for it. What did she pay originally for it?
Let $x$ be the amount she originally paid for the bike, we have:

$300 =$ 80% of $x$

$\Rightarrow 300 = \frac {80}{100} \times x$

$\Rightarrow 300 = 0.8x$

$\Rightarrow x = \frac {300}{0.8} = 375$

3. awesome =] thanks!

4. Originally Posted by Sazza
Hey, just needing some help here:

How much simple interest would be paid on a $700 loan for 5 years (60 months i think, it's easier if you convert to months) at a rate of interest 18%: [my workings: prt= 700x18x60/100 is that right?] how would i do it? and also Sarah sold her bike for$300 which is 80% of the amount she originally paid for it. What did she pay originally for it?
simple interest can be calucaleted by the formula PTR/100.and your equation is correct.and that is 700*18*60/100=7*18*60=126*60=7560\$is the answer.

the answer is the buing bike is x and the eq is 80%of x=300 and solving 300*100/80=375.she paid originally375 for it.