11*57+X(1+2+3+.....+56)
=11*57+X(1+56)*56/2
=627+1596X
=19779
X=(19779-627)/1596=12
Your answer is C
<span>The radius of a circle is 7 inches. What is the area?
Solution:<span>
<span>A= 3.14 * (7 in) · (7 in)</span></span><span> <span>
A= 3.14 * (49 in^2)
</span></span><span>A = </span></span><span>153.94</span><span> in^2</span>
AB+BC you will get the length of AC
Hydrogen is around 0.000053% and Helium is around <span>0.000524%</span>
You can’t see it the picture isnt clear
