by + ax < 100(a+b)/98
7/8 : 21/4
5229.8=3.14D^2*3D
478.29= 3.14*D^2/4*3D
1÷3×59×66
5+5
2x+y=4
x+5y=4
solve the equation.sin(3x
-10)=0.4333 for -90<×<90
