Which of the following is an open equation

5x+7=12

12+(-8)=4

25=5(5)

8+0=8

5x+7+12

Step-by-step explanation:

An Open Equation is basically an equation that has many variables that can be either true or false.  And they normally have a(n) mystery variable in them like x or y for example x+4=8.

You can tell by looking at the problems that three of them already have an answer set in stone for what times what equals what or what + what= what you know so using reasoning and deduction you will find out that your answer is 5x+7=12 because it has a mystery variable(x) letting you know that hey you can use more than one variable whether true or false to find out what times 5 plus 7 equals 12.

i do not know the answer

step-by-step explanation:

a is 8.b is 10.c is 10.5. d is -.5

step-by-step explanation:

just minus the smallest number from the biggest.