Complementary angles:
The sum of two complementary angles is 90.
When two complementary angles are adjacent, a right angle is formed.
Supplementary angles:
The sum of two supplementary angles is 180.
When two supplementary angles are adjacent, a straight angle is formed.
Say you were solving 27 + 19. If you were planning on using the friendly numbers strategy, you'd look at the first <span>addend, 27, and determine that</span> the closest "friendly number" here is thirty, which you'd get by adding 3. From there, you can jump to the next friendly number, forty, by adding another 10. So far you'd've added 13, and you'd need another 6 for that too add up to 19, your second addend. After adding 3, 10, and 6 to 27, you'd find your sum, or "final answer"- 46.
I hope this was what you were looking for!
{x+2y+2z=0
{2x+y+z=3
{x-3y-z=1
{x+2y+2z=0
-
{4x+2y+2z=6
{-3x=-6 → x=2
{-3y-z=-1
+
{y+z=-1
{-2y=-2 → y=1
{2+2+2z=0 → 2z=-4 → z=-2
Final triple is
(2; 1; -2)
