Answer:
x = -3
Step-by-step explanation:
The equation of any linear function is y = mx + c, where m is the gradient and c is the y-intercept
The equation of the function is y = -x + 4
The gradient is negative one (hence 1x) and the y-intercept is 4
We need to find what x equals when the y = 7
7 = -x + 4
Rearrange
7 - 4 = -x
-x = 3
x = -3
