Need variable, inequality and solution

Question

How do you use inequalities to solve problems? I was absent and this is make up work and I'm lost...

 

 Marcus needs to bike at least 80 miles this week for his training. If he has already biked 25 miles this week, then how many miles should he bike on each of the 5 remaining days this week?  

Answer 1

Start with 25 miles.  Assuming he bikes the same number of miles x in each of the 5 remaining days, you want the starting amount plus 5x to be at least 80 miles.

 

25 + 5x ≥ 80

 

Solve for x.

 

x ≥ (80 - 25) / 5 = 11

 

x ≥ 11 miles.