Answer:
First you add 1/3 and 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: 5/15 +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:
5+12/15 which is 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:
In multiplication no need to have the same denominator. You multiply nominators by nominators and denominators by denominators. So you get:
17*7/15*1 and you get 119/5
Since 119 and 15 don't have a common factor, so they can't be simplified.
So, the answer is 119/15.