Rick's average score on his first three tests in math is 80.
Let the total score in the three tests be m
This implies
[tex]\frac{m}{3}=80[/tex]Solve for m
m = 80 x 3
m = 240
Let the next test score be n
It implies that
[tex]\begin{gathered} \text{ }\frac{240\text{ + n }}{4}=84 \\ \text{solve for n} \\ 240\text{ + n = 4 x 84} \\ 240\text{ + n = 336} \\ n=336-240 \\ n=96 \\ \\ \text{ He must score 96 on his next test to raise his average to 84} \\ \\ \text{The answer is }96 \end{gathered}[/tex]