Question #9ddf0

4 Answers
Oct 1, 2016

128

Explanation:

We have: 42 (2) / (3) div (1) / (3)

= (42 (2) / (3)) / ((1) / (3))

= ((42 cdot 3 + 2) / (3)) / ((1) / (3))

= ((128) / (3)) / ((1) / (3))

= (128) / (3) cdot (3) / (1)

= (128) / (3) cdot 3

= 128

Oct 1, 2016

It is 128

Explanation:

42 2/3-:1/3

=42 2/3xx3

=42xx3+2/3xx3

=126+2

=128

I used the following properties of division and multiplication:

  • division by a fraction is the same as multiplication by the fraction's reciprocal

a-:b/c=axxc/b

  • distributive property:

axx(b+c)=ab+ac

Oct 1, 2016

128

Explanation:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dividing with fractions: rarr In a nutshell

Step 1 . change all mixed numbers to improper fractions

Step 2 . div rarr xx and flip the next fraction

Step 3 : cancel any numerator with any denominator through xx

Step 4 : ("top x top")/("bottom x bottom")

Step 5 : simplify if necessary.

Step 6 : Keep improper fractions or change to mixed numbers depending on what you have been told to do.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

42 2/3 div 1/3

=128/3 div 1/3 " "larr step 1

=128/3 xx3/1" "larr step 2

=128/cancel3 xxcancel3/1" "larr step 3 and step 4

= 128" "larr step 5. no further simplifying necessary

Oct 4, 2016

42 2/3 -: 1/3=128

Explanation:

color(blue)("For a moment consider just the "42 2/3)

write this as 42+2/3

This is the same as:

" "[42color(magenta)(xx1)]+2/3

But we can write 1 as 3/3 giving:

" "[42color(magenta)(xx3/3)]+2/3

" "[126/3]" "+2/3 = 128/3

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
color(blue)("Putting it all together")

42 2/3 -: 1/3" "=" "128/3-:1/3

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
color(blue)("Shortcut method")
Turn the 1/3 upside down and multiply

128/3xx3/1 " "=" "3/3xx128/1 " "=" "1xx128" "=" "128

Or by cancelation (which is the same thing really):

128/(cancel(3))xx(cancel(3))/1 = 128/1=128