I need to complete the following number sentences so that the answer to each is 1

Question

12/15 -7/15 + /15 =1

Answer 1

12/15 -7/15 + x/15 =1
or
12 - 7 + x = 15
x = 15 - 12 + 7
x = 10

Answer 2

25/20+16/20+1/20-*/20=1
explain it to me please

Answer 3

25/20+16/20+7/20-x/20=1

Answer 4

In the first problem, since all the denominators were the same, namely 15, I multiplied each term by 15

in the second problem, notice that all denominators are 20, so multiply each term by 20 to get

25 + 16 + 7 - x = 20

easy to solve for x

Answer 5

25/20 +16/20 +1/20 - x/20 = 1

25+16+1-x=20

x=160

Answer 6

18/20 -6/20+ x/20=1

x=20-18+6

x=8
is this the correct answer