Abby made the following conjecture: The sum of a multiple of 7 and a multiple of 8 will be an odd number. Do you agree or disagree? Briefly justify your decision with a counterexample if
possible.

Disagree. As long as the odd number (7) is multiplied by an even number, the sum of multiples of an odd and even number in general will add to be even.

Step-by-step explanation:

Assume you have a=7 and b=8.

Now there are 4 combinations since there are only two types of numbers: even and odd.

Combination 1 would consist of an ODD amount of multiples of a, and and ODD amount of multiples of b.

     See:  3a + 3b

              3(7) + 3(8) = 45

*Combination 2 would be an EVEN amount of a and an EVEN amount of b.

         2a + 2b

         14 + 16 = 30

HERE, in combination 2, the claim is already debunked.

Combination 3 is an ODD amount of a and an EVEN amount of b

         1a + 2b

        7 + 16 = 21

*Combination 4 is an EVEN amount of a and an ODD amount of b

         2a + 1b

         14 + 8 = 24

HERE, in combination 4, the claim is justified again

the simplified form is

step-by-step explanation:

we want to simplify the expression,

let us change the middle bar to a normal division sign to obtain,

we multiply the first fraction by the reciprocal of the second fraction to obtain,

we factor to obtain,

we cancel the common factors to get,

we simplify to get,

the correct answer is b