12×9+12−12×10
=12×(9+1−10)
=12×0
=0
4860÷6=810
5+x=10
x=10-5
x=5
10+x=12
x=12-10
x=2
30x5x2
=30x(5x2)
=30x10
=300
x+4×5=35
x+20 =35
x = 35 -20
x = 15
vun vút, hun hút