Question

What is -17/24-1/15

Answer 1

Hey Fina :) Welcome to OpenStudy!

\[\Large\rm -\frac{17}{24}-\frac{1}{15}\]In order to do the subtraction, our fractions must have the same `denominator`.

Answer 2

One way to determine a suitable denominator is by multiplying the denominators together. But that gives us a really big nasty number that we don't want to deal with :(

Let's instead see what factors our denominators `share`.

Answer 3

24 is 8 times 3,
15 is 5 times 3,
\[\Large\rm -\frac{17}{8\cdot \color{orangered}{3}}-\frac{1}{5\cdot\color{\orangered}{3}}\]Notice they have the 3 in common.
So our common denominator will be the `least common multiple of 24 and 15`.
Which in this case ends up being 3*5*8 = 120

Answer 4

So it looks like our first fraction needs a 5,
while our second fraction needs an 8.

Answer 5

So we'll give our first fraction a 5 (both top and bottom),\[\Large\rm -\frac{17\cdot5}{8\cdot5\cdot \color{orangered}{3}}-\frac{1}{5\cdot\color{\orangered}{3}}\]And we'll give our second fraction an 8 (in both the top and bottom),\[\Large\rm -\frac{17\cdot5}{8\cdot5\cdot \color{orangered}{3}}-\frac{1\cdot8}{8\cdot5\cdot\color{\orangered}{3}}\]

Answer 6

Simplify some stuff before doing subtraction:\[\Large\rm -\frac{85}{120}-\frac{8}{120}\]

Answer 7

Then to do the subtraction, you only subtract the `numerators`, the denominators stay the same.

Got it from there? :)