Step-by-step explanation:
1. 1/4(x + 12)=2 - first isolate X'
- 12 -12
2. 1/4(x) = -10 - 1/4 since its a fraction, you'll have to subtract not divide
-1/4 - 1/4
3. x = -10.25
Andre did the first step correctly, but on the second step he just divided 1.4 by -10, instead of subtract 1/4 from both sides.
if the diameter is 15, its radius is half that, or 7.5
![\bf \textit{area of a circle}\\\\A=\pi r^2~~\begin{cases}r=radius\\[-0.5em]\hrulefill\\r=7.5\end{cases}\implies A=\pi 7.5^2\implies A=56.25\pi \\\\\\A\approx 176.71459\implies A = \stackrel{\textit{rounded up}}{177}](https://tex.z-dn.net/?f=%5Cbf%20%5Ctextit%7Barea%20of%20a%20circle%7D%5C%5C%5C%5CA%3D%5Cpi%20r%5E2~~%5Cbegin%7Bcases%7Dr%3Dradius%5C%5C%5B-0.5em%5D%5Chrulefill%5C%5Cr%3D7.5%5Cend%7Bcases%7D%5Cimplies%20A%3D%5Cpi%207.5%5E2%5Cimplies%20A%3D56.25%5Cpi%20%5C%5C%5C%5C%5C%5CA%5Capprox%20176.71459%5Cimplies%20A%20%3D%20%5Cstackrel%7B%5Ctextit%7Brounded%20up%7D%7D%7B177%7D)
Start by calculating minutes until 4:00. So, from 3:16 to 3:20, there is 4 minutes, then from 3:20 to 4:00 there is 40 minutes. 44 minutes total. Then, from 4:00 to 6:00 there is 2 hours. The total time he is at the party is 2 hours and 44 minutes.
The two numbers in each column have to add to 23
So under 7 you write 16, above 4 you write 19, etc
The rule will say x + y = 23
Solve for w.
2=2(lw+lh+wh)
Flip the equation.
2hl+2hw+2lw=2
Add -2hl to both sides.
2hl+2hw+2lw+−2hl=2+−2hl
2hw+2lw=−2hl+2
Factor out variable w.
w(2h+2l)=−2hl+2
Divide both sides by 2h+2l.
w(2h+2l) / 2h+2l=−2hl+2 / 2h+2l
w=−hl+1/h+l
