This is how you figure out an equation to go along with a table of values chart

first you take the difference between the output number and if it’s negative then you put negative and the number along with x but in our case it’s positive 3x then you add or subtract the difference between the result of 3x, x being the input number then you’d get +17 in our case and you’d check to see if the equation works with all 3 or 4 numbers you have and it should.