How would i simplify this?

Bobs burgers bam has a special deal of 4 hamburgers for $6. at that rate, how much should it cost to buy 3 hamburgers?

Kilgore trout creates a new scale to diagnose depression. however, his scale only assesses one symptom of depression while ignoring others. which of the following is his new scale most likely lacking? a) test-retest reliability b) discriminant validity c) criterion validity d) alternate-forms reliability e) content validity f) none of the above

Find the value of x. also give me an explanation so i can complete it to other questions as well, : )