9e+4=-5e+14+13e
x^2-100x-3824=0
|1 2 -2 | ...
4r-3=3(3r+4)
42+21-x=57
\dfrac{x}{x + 15} = \dfrac{4}{9}
4b+5=1+5b
9g=3(-4+5g)
make a the subject of the formula:
3b = 10c - 7a / 4
\dfrac{5x + 1}{3x - 4} = \dfrac{16}{5}
