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

First, let's make y the subject of the equation.

Let's achieve this by having only y on the left hand side of the equation. To do this we need to minus 3x from both sides of the equation. This leaves us with: 5y = 7 - 3x. Now we must divide both sides by 5. This leaves us with y = 1.4 - 3/5x.

We know that the gradient of a straight line can be found by looking at the number in front of the x. (y = mx + c) In this case, that number, or the gradient, is -3/5.