Solving by substitution
This task is about working out the value of an algebraic expression by substitution.
Show how to find out what each expression equals by substituting the given value into it.
a) 
If p = 7, show how to find the value of 4(p + 3)


b) 
If m = ⁻3, show how to find the value of 4 + 2m


c) 
If r = 3, show how to find the value of 4r^{2}


d) 
If s = ⁻3, show how to find the value of (s + 6)(s + 3)
