00:01
Let's start from question a.
00:03
Here i have to find x and y and now i will define what this x and y are.
00:10
X is an age of a man, y is an age of his son.
00:15
And now let's see what's given in the task.
00:18
Five years ago a man was twice as old as his son, and ten years later the man shall be twice older, than his son.
00:37
So that's a system of equations which i have to solve.
00:42
Now let's open the bracket and now let's calculate the difference between these two equations.
00:48
So i will subtract equation one from equation to then 5 becomes equal to 15 becomes equal to negative y minus 35 or actually let's do it in an opposite way and i'll still yeah, let's subtract two from one.
01:22
So now let's find y.
01:23
Y will be, y is then 20.
01:31
Or actually here i have to be a little bit more accurate with signs...