First question:
interest rate is 5% annually. After 4 years relative value of interest will be 1.05^4
Now we multiply that with starting funds and get
4000* 1.05^4 = 4862.03
Second question:
Because interest is 8% semiannually that means that after 35 years relative value of interest will be 1.04^(35*2)
6000*1.04^70 = 93,429.71
Third question:
after first year tractor's value will be 0.86*15450. After 3 years its value will be:
(0.86)^3*15,450 = 9,827.07
45m+10n-30m
15m+10n
I believe this is right.
Alex bought all the string needed for $125.
It costs $18 for the remaining materials to make each puppet.
So if we closely observe then we see that here $125 is the fixed cost because its not going to change with number of puppets.
And the variable cost is $18.
In this case we can model a Total cost function C(x) for for x number of puppets as below

The total cost to make 50 puppets=$1025
The time take for the cyclist to travel from Fort Worth to Fresno is 
Explanation:
It is given that the distance from Fort Worth to Fresno is 1,530 miles.
The average speed of the cyclist is 17 miles per hour.
The time travelled by the cyclist can be determined using the formula,

Substituting the value of distance and speed, we get,

Dividing both sides by 17, we get,

Thus, the time take for the cyclist to travel from Fort Worth to Fresno is 