Tim spends 500 minutes at the school.
Step-by-step explanation:
Given,
Time for lunch = 45 minutes
Time for study hall = 45 minutes
Total = 45+45 = 90 minutes
This represents 18% of the total minutes Tim spend at school.
Let,
x be the total minutes Tim spend at school.
18% of x = 90 minutes

Dividing both sides by 0.18

Tim spends 500 minutes at the school.
Keywords: percentage, division
Learn more about division at:
#LearnwithBrainly
When it doesn’t look like a U anymore and is upside down
Looking at an equation than when x is negative
You question implies simple subtraction is needed:
28-8=20
Answer:

Step-by-step explanation: