Please help asap test is timed

The solution set for 5v2 – 125 = 0 is

What is the number 321,000,000 in scientific notation? also what is the number? ?

Marco has $38.43 dollars in his checking account. his checking account is linked to his amazon music account so he can buy music. the songs he purchases cost $1.29. part 1: write an expression to describe the amount of money in his checking account in relationship to the number of songs he purchases. part 2: describe what the variable represents in this situation.