The line AB has equation 3x + 5y = 7. What is the gradient of AB?

The gradient of a line in the form y = ax + b, where a and b are some numbers, is the number a.

So we need to get the equation 3x + 5y = 7 into the above form, with y on one side on its own!

We first move the 3x to the right hand side by subtracting 3x from both sides, giving us

5y = -3x + 7.

We then divide both sides by 5 to give us 

y = (-3/5) x + (7/5).

So our number a in this case is -3/5, which is our gradient!