differentiate y=-2/3x^6
6^2+4/(3*8)-8
5y-7=185y-7=18
a+b=10
x+a=20
x+b=24
a.b'+c=1
a+c=1
x+y=20
x+z=24
400 divide by 20*10^-4
\pi \times 4^2\times 10
( (-8)-6 -(-4) ) /5
2/9*11/6*5/6
18/24 divided by three
