Help me!!! Please to solve this problem of o. Math

a) Given a function f(x) = 2x + 3. Find (a) f(1), (b) f(-5), (c) f(a), (d) f(a + 2) (e) f(b)?

b) let f(x) = x + 4 define a function in the closed interval of -55x55, find f(-2), f(3) and f(7). ​