Money math (please answer soon )

Question

2/3 connor earned in his last year is the same as a 4th of the money he earned this year. If Connor earned 400 more dollars than last year how much money did he earn last year?

Answer 1

let "L" be the amount of money Connor earned last year and "T" the amount of money he earned this year.

Then we can say:

1) 2/3L = 1/4T

2) L + 400 = T

Since "T" is the same as "L + 400" we can substitute "L + 400" for "T" in the 1st equation to get:

2/3L = 1/4(L + 400)

2/3L = 1/4L + 100

2/3L - 1/4L = 100

8/12L - 3/12L = 100

5/12L = 100

l = 100(12/5)

L = 240

So last year he earned $240