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alex estimates that if he lies in the sun for k hours it will take him (10+10k) to get to sleep at night because of the sunburn
. If Alex wants to get as much sun as possible without taking more than half an hour to get to sleep, how many HOUR CAN he lie in the sun?
A 1/2
B 1
C 2
D 2 1/2
E 3

Math 
Steve,
If 10+10k is the number of MINUTES it takes to get to sleep,
10+10k <= 30
k <= 2