Remember the f(x) is the same thing as y so...
y = -3x + 5
y = -1
To solve this plug -1 in for y in the equation y = -3x + 5 and solve for x
-1 = -3x + 5
-6 = -3x
2 = x
When f(x) is -1 then x is 2
Hope this helped!
~Just a girl in love with Shawn Mendes
