Given the equation
2x + 5y = 7,
answer the following questions.
(a) is the slope of the line described by this equation positive or negative?
positive
negative

(b) as x increases in value, does y increase or decrease?
increase
decrease

(c) if x decreases by 5 units, what is the corresponding change in y?

To answer these questions it is easiest first to put the equation in the form y = mx+c. This is done by rearranging to form 5y = -2x + 7 and then dividing by 5 to form y = -0.4x + 1.4. Question (a) The slope of this line is negative. The "m" part of the equation describes the gradient of the line which in this case in negative. Question (b) As x increases in value y will decrease as the value of x is multiplied by a negative 2.Question (c) If x decreases by 5 units the value of y will increase by 2 units. This can be tested by inserting values into the equation.