Question

Shelby's test scores are 99, 91, and 85. If she must average at least 90 points to get an A in the class, what must she earn on the next test?

Okay so this was my equation but it came out completely wrong.

99+91+85+x greater than or equal to 90

So what should the equation be?

Answer 1

You're very close but you left out one thing. You have to divide to find averages, so:
(99+91+85+x)/4>=90
99+91+85+x=360
Take it from here.