Questio Matteo scored 85 on their first test, 89 on their second test, 85 on their third test, and
89 on their fourth test. Suppose Matteo has one more test in the semester and wants
to finish with a mean score of 88.

What score do they need on their last test to finish with a mean score of 88?

i used to know how to do this in 7th but i forget easily

step-by-step explanation:

20/27

​​

step-by-step explanation:

1 simplify brackets

-\frac{8}{9}\times \frac{5}{6}−

​9

​

​8

​​ ×

​6

​

​5

​​

2 use this rule: \frac{a}{b}\times \frac{c}{d}=\frac{ac}{bd}

​b

​

​a

​​ ×

​d

​

​c

​​ =

​bd

​

​ac

​​

-\frac{8\times 5}{9\times 6}−

​9×6

​

​8×5

​​

3 simplify 8\times 58×5 to 4040

-\frac{40}{9\times 6}−

​9×6

​

​40

​​

4 simplify 9\times 69×6 to 5454

-\frac{40}{54}−

​54

​

​40

​​

5 simplify \frac{40}{54}

​54

​

​40

​​   to \frac{20}{27}

​27

​

​20

​​