With this one, since the problem says it will cost $35 per hour, then that will be based on the amount of hours spent on the job, so 35 gets the x, with x equaling the number of hours it took to do the job. $78 is the cost for a part so it is going to stay at 78. So your answer will be D. 35x+78≤225.
The club needs to make and sell 29 t-shirts in order to profit at least 150.
<em><u>Explanation</u></em>
Suppose , the number of t-shirts the club needs to make and sell is 
Selling price of each t-shirt is 15, so the total selling price of
t-shirts 
It costs 20 plus 9 per t-shirt to make the t-shirts. So, the total making cost of
t-shirts 
Now for getting profit at least 150 , the equation will be.....

It means the value of x should be at least 28.333...
<em>As here x is the number of t-shirts and it can't be in decimal , so </em><em>the minimum value of x will be 29.</em>