I need help.............​

15.

16.

17.

Step-by-step explanation:

In order to add or subtract two fractions with different denominators more easily, find the LCM of the denominators and solve by adding or subtracting the numerator.

LCM - Lowest Common Multiple

The lowest common multiple is the number that shows up earliest that is in both numbers' multiples.

Example: LCM of 2 and 3

2, 4, 6, 8, 10...

3, 6, 9, 12, 15...

Because 6 is the number that shows in both sets first, 6 is the LCM.

We will use this process to solve each problem:

15:

+           Because the denominators are the same, adding can be done immediately.

                 To put this into simplest form, divide by    .

÷             Divide.

16:

+              The LCM of 5 and 6 is 30. So, multiply by and by .

× + ×   Multiply.

+           Add the fractions.

                 Because 37 is a prime number, this is the simplest form.

17:

-               The LCM of 6 and 9 is 18. So, multiply by and by .

× - ×    Multiply.

-            Subtract the fractions.

                 Because 7 is a prime number, this is the simplest form.