SOLUTION: On his first two social studies tests, Billy made an 86 and a 93. What grade must Billy make on the third test to have an average of 90 for all three tests?

Question 867293: On his first two social studies tests, Billy made an 86 and a 93. What grade must Billy make on the third test to have an average of 90 for all three tests?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
On his first two social studies tests, Billy made an 86 and a 93. What grade must Billy make on the third test to have an average of 90 for all three tests?
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Let the 3rd test score be "x"::
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Equation::
(86+93+x)/3 = 90
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179 + x = 270
x = 91
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Cheers,
Stan H.
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