An equivalent ratio would be 7:10 or 70:100 or 42:60 and so on...
Sum means add
the number is x
13 divided by a number is 13/x
the number divided by the number is x/13
so

also can be simplified to

or

translated it is

where x is the number
Answer:
Step-by-step explanation:
13 - [4 *(8 - 5) + 2 - 9] * 2 =
13 - [ 4 (3) + 2 - 9] * 2 =
13 - [ 12 + 2 - 9] * 2 =
13 - 5 * 2 =
13 - 10 =
3