Can someone check my answers?

The amount of money in Alexander’s account is, = 4000 − 70, where is the amount in dollars and is the time in weeks.

a) Which variable is independent and which is dependent?

Dependent is -70x and independent is 4000

b) In which week will there be $1701 in the account?


y=4000-70(x)
1701=4000-70(x)
-70x=1701-4000
-70x= -2299
x=-2299/-70
x=2299/70
x=32.843
x=33

c) How much will the amount in Alexander’s account change if the time increases by 15 weeks?


y=4000-70(x)
y=4000-70(15)
y=2950