The average allowsnce money of ernest jack david and mike is 123 per month per person. the average allowance of ernest jack and david is 159 per month per person. david's monthly allowance is 2 less than mikes and mikes monthly allowance is 1/18 of jacks. how much allowance does ernest get

Ernest gets 194 monthly allowance

Step-by-step explanation:

* Lets revise the rule of the average

- Average = The sum ÷ the total number

- Assume that the allowances money of Ernest, Jack, David and Mike

  are E, J, D, M respectively

∵ The average allowance money of Ernest jack David and mike is

   123 per month per person

∴ 123 = (E + J + D + M) ÷ 4

- Multiply both sides by 4

∴ E + J + D + M = 492 ⇒ (1)

∵ The average allowance of Ernest jack and David is 159 per month

    per person

∴ 159 = (E + J + D) ÷ 3

- Multiply both sides by 3

∴ E + J + D = 477 ⇒ (2)

- Subtract equation(2) from equation (1) to find M

∴ M = 15

* Mike's monthly allowance is 15

∵ David's monthly allowance is 2 less than mikes

∴ D = M - 2

∵ M = 15

∴ D = 15 - 2 = 13

∴ David's monthly allowance is 13

∵ Mikes monthly allowance is 1/18 of jacks

∴ M = × J

∴ 15 = × J

- Multiply both sides by 18

∴ J = 270

* Jack's monthly allowance is 270

- Substitute the values of D , J in equation (2) to find E

∵ D = 13 and J = 270

∵ E + J + D = 477

∴ E + 270 + 13 = 477

∴ E + 283 = 477

- Subtract 283 from both sides

∴ E = 194

* Ernest's monthly allowance is 194

* Ernest gets 194 monthly allowance

the answer i think is a)

step-by-step explanation: