Hey there!
The answer to your question is 
Given:
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First, we can start by adding like terms. The following are like terms:



Now, we can add these pairs together, giving us:



Now, add all this together, and we get our answer as:
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Have a terrificly amazing day!
Answer:
a. 2:3, b. 25 students, c. 3:2
Step-by-step explanation:
a. 5 (total) - 2 (with glasses) = 3 (without glasses), making the ratio 2:3.
b. We can assign the total students with the variable x. 3:5=15:x, 75=3x, x=25. 25 total students.
c. 25 (total students) - 15 (without glasses) = 10 (with glasses). (10+5):(15-5) is 15:10, which, when simplified, equals to 3:2.