Jenna bought a gallon of milk at the store for $3.58. about how much change did she recevie from $20 bill?

So 3.58 and a 20.00 dollar bill  we subtract
20.00-3.58
break it up
20=4+16
16+4-3.58
focus on the 4.00-3.58 part
4.00=3.00+1.00
3.58=3.00+0.58
1.00+3.00-3.00-0.58
1.00-0.58=1.00-(0.60-0.02)=1.00-0.60+0.02=0.40+0.02=0.42

$16.42 is the change

)because it's going in order of the math sign