Question

Find the constants m and b in the linear function f(x) = mx + b so that f(1) = 2 and the straight line represented by f has slope - 1.

Answer 1

you were given f(x) = mx + b
when m = slope and b = y-intercept
you were also given f(1) = 2
which means that when x = 1 in the function output (y) = 2
therefore you have been given slope = -1 = m
and point on line = (1, 2)
you understand how to do the rest? :)