Mell is twice as old as jerry. if 16 is subtracted from mell’s age and 16 is added to jerry’s age, their ages will be equal. what are their present ages?

M = Mell

J = Jerry

M = 2J              [Mell is twice as old as Jerry]

M - 16 = J + 16           [When Mell's age is subtracted by 16, and 16 is added to Jerry's age, their ages will be equal]

Since you know M = 2J, you can plug in/substitute 2J for "M" in the second equation:

M - 16 = J + 16

2J - 16 = J + 16    Add 16 on both sides

2J = J + 32         Subtract J on both sides

J = 32

Now that you know Jerry's age, you can find Mell's age:

M = 2J

M = 2(32)

M = 64

Mell is 64, Jerry is 32