How man bags were used?
41 / 3 = 13.7
We can say about 14 bags by rounding to the nearest whole number. Therefore, 14 bags were used.
(ax-by)²+(bx+ay)²
a²x²-2axby+b²y²+b²x²+2axby+a²x²
a²x²+b²x²+b²y²+a²x²
(a²+b²)x²+(a²+b²)y²
(a²+b²)(x²+y²)
First think out the equation, once you've done that multiply 3 by 25 to get 75
Consider the system of inequalities
1. Plot all lines that are determined by equalities (see attached diagram)
2. Determine which bounded part of the plane you should select:
means that you should take points with y-coordinates greater than or equal to 2 (top part of the coordinate plane that was formed by the red line);
means that you should take points with x-coordinates less than or equal to 6 (left part of the coordinate plane that was formed by the blue line);- for
you can check where the origin is placed. Since 
, the origin belongs to the needed part and you have to take the right part of the coordinate plane that was formed by green line. - for
you can check where the origin is placed. Since 
, the origin belongs to the needed part and you have to take the bottom part of the coordinate plane that was formed by orange line.
3. According to the previous explanations, the shaded region is as in A diagram.
Answer: correct choice is A.
-3(5 + 8x) - 20 ≤ -11 |use distributive property: a(b + c) = ab + ac
-15 - 24x - 20 ≤ -11
-35 - 24x ≤ -11 |add 35 to both sides
-24x ≤ 24 |change signs
24x ≥ -24 |divide both sides by 24
x ≥ -1
