Ineed to know if any one can me explain to my son how multi- step equations work like this (8v-7)=12-4v

Two parallel lines are crossed by a transversal. what is the value of x? x = 40 x = 70 x = 110 x = 130

Three baby penguins and their father were sitting on an iceberg 0.50.50, point, 5 meters above the surface of the water. the father dove down 4.74.74, point, 7 meters from the iceberg into the water to catch dinner for his kids. what is the father penguin's position relative to the surface of the water?

Aword processing program requires a 7- digit registration code made up of the digits 1,2,4,5,6,7 and 9 each number has to be used and no number can be used mor than once how many codes are possible