Answer:
Before anyone gives anyone money, Mario has 24 dollars and Roberto has 12 dollars. After they give each other money, both of them have 18 dollars.
Step-by-step explanation:
Mario has twice as much as Roberto, BUT if Mario gives Roberto 6 dollars, then they have the same amount.
M = 2R
M - 6 = R + 6
To isolate M, you need to add 6 on both sides.
M - 6 + 6 = R + 6 + 6
M = R + 12
M = 2R
Substitute M for the value above that we found.
R + 12 = 2R
Now we subtract R on both sides, so that only one side has the variable R.
R - R + 12 = 2R - R
12 = R
M = 2R
Substitute for the value of R.
M = 2 x 12
M = 24
