7 times as much as the sum of 1/3 and 4/5

2 answers:

7 0

First of all, you add 1/3 and 4/5, so you get:
$\frac{1}{3} + \frac{4}{5}$

To add 2 fractions, they need to have the same denominator. Since 3 and 5 don't have a common factor, so you multiply 1/3 by 5, and 4/5 by 3, so you get:
$\frac{1*5}{3*5} + \frac{4*3}{5*3}$
$\frac{5}{15} + \frac{12}{15}$

Now, the two fractions got the same denominator, and you can add them by adding the numerators over the same denominator. (You don't add denominators in addition) so you get:
$\frac{5+12}{15}$
$\frac{17}{15}$

That's the sum of 1/3 + 4/5.

Now, they want the sum of the 2 fractions 7 times. So you multiply 17/15 by 7. And as you know, 7 = 7/1. So you get:
$\frac{17}{15} * \frac{7}{1}$

In multiplication no need to have the same denominator. You multiply nominators by nominators and denominators by denominators. So you get:
$\frac{17*7}{15*1}$
$\frac{119}{15}$

Since 119 and 15 don't have a common factor, so they can't be simplified.
So, the answer is 119/15.

Hope this Helps! :D

Anna11 [10]3 years ago

3 0

What you have to do first is to add $\frac{1}{3}$ and $\frac{4}{5}$ ,

<h2>Further Explanation</h2>

Therefore we have:

= $\frac{1}{3}$ + $\frac{4}{5}$

= ( $\frac{1}{3}$ + $\frac{4}{5}$ ) / 15 (15 is the smallest number that divide both denominator also known as LCD)

= (5 x 1) + (3 x 4) / 15

= 5 + 12 / 15

= $\frac{17}{15}$

Therefore, the sum of $\frac{1}{3}$ + $\frac{4}{5}$ is $\frac{17}{15}$

But since the question says you should determine the sum of the 2 fractions, therefore you should multiply $\frac{17}{15}$ by 7. Therefore you should have:

$\frac{17}{15}$ X 7 (7 can also be expressed as $\frac{7}{1}$ )

= $\frac{17}{15}$ x $\frac{7}{1}$ (notably, in multiplication there is no need for the fraction to have the same denominator. You can multiply both numbers at the top together (numerator) and do same with the denominator.

= $\frac{119}{15}$