How can i use operations to model real world problems?

Twice the sum of a number and 4 is equal to three times the difference of the number and 7. find the number.

Gh bisects fgi. find the measure of hgi •15° •21° •10° •8°

Aproduction manager test 10 toothbrushes and finds that their mean lifetime is 450 hours. she then design sales package of this type of toothbrush. it states that the customers can expect the toothbrush to last approximately 460 hours. this is an example of what phase of inferential statistics