Question

f(x-1)=2x-3 for all values of x then find f(-3)

Answer 1

F(x-1)=2x-3
Now , x-1= -3
x = -2
F(-3) = 2(-2)-3 = -7

Answer 2

equate
$x - 1 = - 3 \\ x = - 2$
put x=-2 in the given equation
we get
$f( - 3) = \: \: 2 \times ( - 2) - 3 \\ f( - 3) = - 7$