Assume the values

int a = 123;
int b = 256;

The following are all valid expressions returning a+b

plus(arg1, arg2)(a, b)
plus(arg1, b)(a)
plus(a, arg2)(a,b)
plus(a, arg1)(b)
plus(a, b)()

The expressions can be combined like this

plus(minus(a, b),b)()
plus(minus(arg1, b),b)(a)
plus(minus(arg1, arg2),b)(a,b)
plus(minus(arg1, arg2),arg2)(a,b)

Other numerical operators can be used like this

multiplies(arg1,arg2)(3,6)
divides(arg2,arg1)(3,6)
modulus(arg2,arg1)(4,6)
min(arg1,arg2)(4,6)
max(arg1,arg2)(4,6)
inc(arg1)(a)
dec(arg1)(a)
negate(arg1)(a)