Answer:
19.488
Step-by-step explanation:
8.12 x 2.4 = 19.488
When Sam is 13 his mother will be 39 which is 3 times as old as he is. So Sam's mother will be 3 times as old as Sam will be in 11 years. (Your answer is 11 years.)
Distribute the .25 to get .25x + 1 - 3 = 28
Then simplify to get .25x - 2 = 28
Move the two to the right to get .25x = 30
Then divide to leave x: 30 / .25 = 120
X = 120
You know that two expressions are equivalent when if you substitute in your values and simply the expressions, they have the same answer.
