how do i solve 3-f=5/6

Question

my daughter is stumped on this problem.  I would like her to understand how to get this answer.

Answer 1

3 - f = 5/6

subtract 3 from both sides using the common denominator of 6

so 3 = 18/6

so -f = 5/6 - 18/6

-f = -13/6

divide both sides by -1

f = 13/6