Question

A student solved this problem and said the answer is 5 pounds.

Answer 1

No, the students answer is decently far off the correct answer would be 1 7/10 pounds because, to add fractions you first need to find a common denominator that both of the numbers go into for example for this one 10 is a common denominator because 5 goes into 10 twice and 10 goes into 10 once so we multiply 4/5 by 2 because it take twice the amount of 5 to get to 10 and what we do to one side we must replicate on the other side as well. Like so,
4/5*2=8/10 now all the we have to do is take 8/10+9/10=17/10 and simplifying that down you get 1 7/10 because 10 goes into 17/10 one time with 7 left over and because 7 is prime that answer can not be simplified down any more.

Enjoy!=)

Answer 2

The answer is no, because the net weight or the pounds the packages weigh together isn't close to 5 pounds---------->

given
two packages of hamburgers
4/5 of a pound, package 1
9/10 of a pound, package 2
--------------------------------
10/10 =1pound
5X 10/10= 50/10= 5pounds
first convert both to same denominator, find the lowest common multiple between the denominators, 10,5
10 is the smallest so lets turn all answer into something over #/10
4    X
-- = --
5     10
    √
5x2=10
what ever you multiply the bottom you multiply to the top
we multiplied the bottom by 2 so we need to multiply the top by 2/ 4X2=8
 8
 --
10
-------------
since 9/10 already has 10 in the denominator we can keep this as this is
-----------------------------------------------------------------------------------
 8     9    17         7   17                                          17                    50
 -- + --= --- = 1  -- =---pounds of hamburgers.    -- ≠5 pound/  --- pounds
10   10   10        10   10                                        10                     10

≠ doesn't/don't equal

check with teacher