He fourth one: 4,5,6,7,8...if it has those two bars || it means absolute value which basically means if its negative you just change it to a posotive :)
Answer:
x = 7.5
Step-by-step explanation:
10/4 = 2.5
x = 3 × 2.5 = 7.5
Another way
x = 3/4 × 10 = 7.5
