Question

If the average of four number is 20,what is the first and last number?​

Answer 1

Answer:

10,40

Step-by-step explanation:

${x + 2x + 3x + 4x} \div 4 = 20 \\ 10x \div 4 = 20 \\ 10x = 100 \\ x = 10 \\ 1x = 10 \\ 4x = 40$