1/a-1/b=1/c=1/d find the value of C , if a=1/2 , b=1/4 and d=-1/5

Plz which expression is equivalent to the expression below?

Which multiplicative property is being illustrated below? (type commutative, associative, or identity) 5 × 2 × 4 = 2 × 5 × 4

What is the expression in factored form? -20x^2 - 12x a. 4x(5x+3) b. -4x(5x-3) c. -4(5x+3) d. -4x(5x+3)