Determine the equation

In a graph with several intervals o data how does a constant interval appear? what type of scenario produces a constant interval?

Players on the school soccer team are selling candles to raise money for an upcoming trip. each player has 24 candles to sell. if a player sells 4 candles a profit of$30 is made. if he sells 12 candles a profit of $70 is made

Aline passes through 3,7 and 6,9 what equation represents the line