Step-by-step explanation:
it just means to convert these equations into function definitions.
and a function looks like
y = ... something with x, factors, other functions, constants
1)
x + y = z
y = -x + z or z - x
2)
x - y = z
x - z = y or y = x - z
3)
x × y = z
y = z/x
4)
x/y = z
x = z × y
x/z = y or y = x/z
