3.) A *the first one*
4.) C *the last one*
Option C:
is the value of a and b
Explanation:
Given that the expression 
We need to determine the value of a and b
Let us consider the term
and take the prime factorization of the term 648
Thus, we have,
648 divides by 2,

324 divides by 2,

162 divides by 2,

81 divides by 3,

27 divides by 3,

9 divides by 3,

Thus, we have,

Therefore, equating the powers of 2 and 3, we get,

Hence, the value of a and b is 3 and 4
Thus, Option C is the correct answer.
I hope this helps you
-4x-2y+4x+8y= -12-24
6y= -36
y= -6
-4x-2. (-6)= -12
-4x+12= -12
-4x= -24
x=6
(6, -6)
Hope this helps let me know if you need help
So you have
8 digits (number available) to form
3 digit numbers (number selected).
Using the formula

where a is the number of available digits, P is the permutation function and c is the number of digits to be selected.
The number of three digit numbers that can be formed =

=
336 <span>
O R</span>By using the formula

where a is the number of available digits and c is the number of digits to be selected.<span>
</span>⇒

<span>
</span>⇒

<span>
</span>⇒ Permutation =
336<span>
</span>