Answer:
78
Step-by-step explanation:
Let x be the score on the next test
We are averaging 6 tests and want an average of 75
( 82+91+38+78+83+x) /6 = 75
Multiply each side by 6
( 82+91+38+78+83+x) = 75*6
( 82+91+38+78+83+x) =450
Combine like terms
x+372 = 450
Subtract 372 from each side
x+372-372 = 450-372
x =78
