<span>4 graders sold 4 times as many erasers as the students in fifth grade
</span>so
684 / 4 = 171
answer
students in 5 grade sold 171 <span>erasers </span>
![\bf ~~~~~~\textit{initial velocity} \\\\ \begin{array}{llll} ~~~~~~\textit{in feet} \\\\ h(t) = -16t^2+v_ot+h_o \end{array} \quad \begin{cases} v_o=\stackrel{}{\textit{initial velocity of the object}}\\\\ h_o=\stackrel{}{\textit{initial height of the object}}\\\\ h=\stackrel{}{\textit{height of the object at "t" seconds}} \end{cases} \\\\[-0.35em] ~\dotfill\\\\ h=-16t^2+\stackrel{\stackrel{v_o}{\downarrow }}{65}t](https://tex.z-dn.net/?f=%5Cbf%20~~~~~~%5Ctextit%7Binitial%20velocity%7D%20%5C%5C%5C%5C%20%5Cbegin%7Barray%7D%7Bllll%7D%20~~~~~~%5Ctextit%7Bin%20feet%7D%20%5C%5C%5C%5C%20h%28t%29%20%3D%20-16t%5E2%2Bv_ot%2Bh_o%20%5Cend%7Barray%7D%20%5Cquad%20%5Cbegin%7Bcases%7D%20v_o%3D%5Cstackrel%7B%7D%7B%5Ctextit%7Binitial%20velocity%20of%20the%20object%7D%7D%5C%5C%5C%5C%20h_o%3D%5Cstackrel%7B%7D%7B%5Ctextit%7Binitial%20height%20of%20the%20object%7D%7D%5C%5C%5C%5C%20h%3D%5Cstackrel%7B%7D%7B%5Ctextit%7Bheight%20of%20the%20object%20at%20%22t%22%20seconds%7D%7D%20%5Cend%7Bcases%7D%20%5C%5C%5C%5C%5B-0.35em%5D%20~%5Cdotfill%5C%5C%5C%5C%20h%3D-16t%5E2%2B%5Cstackrel%7B%5Cstackrel%7Bv_o%7D%7B%5Cdownarrow%20%7D%7D%7B65%7Dt)
now, take a look at the picture below, so for 2) and 3) is the vertex of this quadratic equation, 2) is the y-coordinate and 3) the x-coordinate.
![\bf \textit{vertex of a vertical parabola, using coefficients} \\\\ h=\stackrel{\stackrel{a}{\downarrow }}{-16}t^2\stackrel{\stackrel{b}{\downarrow }}{+65}t\stackrel{\stackrel{c}{\downarrow }}{+0} \qquad \qquad \left(-\cfrac{ b}{2 a}~~~~ ,~~~~ c-\cfrac{ b^2}{4 a}\right) \\\\\\ \left( -\cfrac{65}{2(-16)}~~,~~0-\cfrac{65^2}{4(-16)} \right) \implies \left( \cfrac{65}{32}~,~0- \cfrac{4225}{-64}\right)](https://tex.z-dn.net/?f=%5Cbf%20%5Ctextit%7Bvertex%20of%20a%20vertical%20parabola%2C%20using%20coefficients%7D%20%5C%5C%5C%5C%20h%3D%5Cstackrel%7B%5Cstackrel%7Ba%7D%7B%5Cdownarrow%20%7D%7D%7B-16%7Dt%5E2%5Cstackrel%7B%5Cstackrel%7Bb%7D%7B%5Cdownarrow%20%7D%7D%7B%2B65%7Dt%5Cstackrel%7B%5Cstackrel%7Bc%7D%7B%5Cdownarrow%20%7D%7D%7B%2B0%7D%20%5Cqquad%20%5Cqquad%20%5Cleft%28-%5Ccfrac%7B%20b%7D%7B2%20a%7D~~~~%20%2C~~~~%20c-%5Ccfrac%7B%20b%5E2%7D%7B4%20a%7D%5Cright%29%20%5C%5C%5C%5C%5C%5C%20%5Cleft%28%20-%5Ccfrac%7B65%7D%7B2%28-16%29%7D~~%2C~~0-%5Ccfrac%7B65%5E2%7D%7B4%28-16%29%7D%20%5Cright%29%20%5Cimplies%20%5Cleft%28%20%5Ccfrac%7B65%7D%7B32%7D~%2C~0-%20%5Ccfrac%7B4225%7D%7B-64%7D%5Cright%29)
![\bf \left( \cfrac{65}{32}~,~0+ \cfrac{4225}{64}\right)\implies \left( \stackrel{seconds}{2\frac{1}{32}}~~,~~ \stackrel{feet~hight}{66\frac{1}{64}}\right)](https://tex.z-dn.net/?f=%5Cbf%20%5Cleft%28%20%5Ccfrac%7B65%7D%7B32%7D~%2C~0%2B%20%5Ccfrac%7B4225%7D%7B64%7D%5Cright%29%5Cimplies%20%5Cleft%28%20%5Cstackrel%7Bseconds%7D%7B2%5Cfrac%7B1%7D%7B32%7D%7D~~%2C~~%20%5Cstackrel%7Bfeet~hight%7D%7B66%5Cfrac%7B1%7D%7B64%7D%7D%5Cright%29)
Answer:
See explanation
Step-by-step explanation:
The texts in the question is distorted and unclear; So, I will provide a general explanation of solving an equation with 1 variable.
A similar question that can be found online is:
--- to solve for x
First, collect all like terms
![8x - 4x = 8 + 12](https://tex.z-dn.net/?f=8x%20-%204x%20%3D%208%20%2B%2012)
Distribute the expression on the left-hand side
![x * 4 = 8 + 12](https://tex.z-dn.net/?f=x%20%2A%204%20%3D%208%20%2B%2012)
Simplify like terms
![x * 4 = 20](https://tex.z-dn.net/?f=x%20%2A%204%20%3D%2020)
Divide both sides by 4
![x = 5](https://tex.z-dn.net/?f=x%20%3D%205)
Because when you multiply by 10, it adds a zero to the end of the number, like 12*10 = 120, so vise versa for dividing