Malik is working two summer jobs, making $7 per hour babysitting and making $18 per hour lifeguarding. In a given week, he can work a maximum of 15 total hours and must earn at least $160. If Malik worked 8 hours lifeguarding, determine the minimum number of whole hours babysitting that he must work to meet his requirements.
Let's say Malik worked x hours babysitting.
The total number of hours worked is x+8.
The total money earned from babysitting is 7x.
The total amount of money earned from lifeguarding is 8*18=$<<8*18=144>>144.
The total amount of money Malik has earned is 144+7x.
The equation representing the two circumstances is 144+7x >= 160.
So 7x >= 160 - 144
7x >=16
x >=16/7.
The minimum whole number of hours Malik must babysit to meet his requirements is 3. Answer: \boxed{3}.