We start to solve this by looking for the formula that let us calculate an average value, this formula would be:

where Save is the average score and s is the score of each exam, Since we know the value of the score Save and 4 of the exams we can replace them in the formula, like this:
And we can solve for s5, which is the score that we need to find, like this:

Then, Pedro must have a 55 score on the fifth test
Answer:
-4<x<-1
Step-by-step explanation:
To solve the problem, we divide the whole expression by 2:
2x^2 + 10x < –8 → x^2 + 5x < –4
→ x^2 + 5x + 4 < 0
Factorizing
→ (x+4)(x+1) < 0
The expression is ONLY negative when:
x>-4 and x<-1
Therefore, the solution is:
-4<x<-1