Question

The average of 3, 15, and my number is 40. What is my number? I'll give 30 points!

Answer 1

Answer:

102

Step-by-step explanation:

The average is calculated using

average = $\frac{totalscore}{count}$

let your score be x, then

$\frac{3+15+x}{3}$ = 40 ( multiply both sides by 4 )

18 + x = 120 ( subtract 18 from both sides )

x = 102 ← your number