Answer:
the relation between them are
n(U) = n(X U Y) + n(xūy).
In mathematical notation, ∑ means summation. So wherever you see the symbol, you have to sum over all elements in the set. Let's solve the question.
a. ∑m means, to sum all elements in the set m: ∑m = 12 + 15 + 20 + 30 = 77
b. ∑
means to sum all elements in the set f as the square of the elements f = 
c. ∑mf means to sum all elements as the product of the elements of m and f = (12×5) + (15×9) + (20
10) + (30×16) = 875
d. ∑
means to sum all elements as the product of the square of m and f = 
OKay i willl help what are the questions
3(x-5)-4(x+3)
Multiply the first bracket by 3
(3)(x)=3x
(3)(-5)=-15
(-4)(x)=-4x
(-4)(3)=-12
3x-15-4x-12
3x-4x-15-12 ( combine like terms)
Answer: -x-27