When x=1, 7x+3 = 10. When x=2, 7x+3 = 17. When the value of 'x' changes from '1' to '2', the value of 7x+3 changes from '10' to '17' . . . a distance of '7' . That's what the ' 7x ' in the equation means, and that's what we mean when we say that the 'slope' of the equation is '7'. 'y' changes '7' for every '1' that 'x' changes. Hope this helps :))