Estimate an 18% tip for a $30.80 meal

My math teacher told my class to "steal" a 6th grade fraction word problem from the internet, word problems? : -p requirements: only a 1 step word problem. needs to be complex.

Solve for x where 0 equation: cot^2x+2cotx+1=0

Libby built a fence that was 56 \text { feet}56 feet long over 44 days. she built the same length of fence each day. how many inches of fence did libby build each day?