18 shells because since Mary has 6 and Tina has 3 shells all you have to do is multiply 6 and 3 to get 18
1/2^3=1/8
we have 30 of them so
30.1/8=30/8 => 3 and 6/8 or 3 and 3/4 if simplified
First we need to multiply to make the fractions have equal denominators so we can add/subtract.
math: 1/3 x 4/4=4/12
science: 1/4 x 3/3=3/12
Now we can find the time she spent on history (I assume this is what you are looking for)
Total time-math time<span>-science time=history time</span>
12/12-4/12-3/12
=5/12
Amy spent 5/12 of her time working on history.
The process of moving a figure to a different location is called TRANSFORMATION.
You would get $15 in total because 5x3=15.