I believe its the second choice.
2.5 x 10⁻²
Move the decimal two places to the right and multiply by 10 to the power of -2
Let c and d be the number of cds and dvds respectively.
c+d=12
c=12-d
The we are told that:
2c+3d=31, using c found above in this equation gives you:
2(12-d)+3d=31
24-2d+3d=31
24+d=31
d=7
So Phillip bought 7 dvds.
check...
3*7+2(12-7)=31
21+2(5)=31
21+10=31
31=31
B I think I don’t really know
72.5%
You can get this by dividing the new price by the original price and then multiplying by 100.