Please show the solutions!

Question

1.) x+y-2(2x-3y)
2.) x+y/2 - 3x-y/4 + x-5y/8
3.) 4x- {3x-[(x-3)-2(x-5)]}
4.) a+5b/2 + a-3b/3 - 5(a-b)/6
5.) 2x-5=3x-9
6.) 3x-(2x-7)=2x+3
7.) 7x+2/6 - x-4/3 = x+3/3
8.) 3x-2(x-3)+3(5-2x)
9.) x+1/3 - x-2/4 - x/6
10) 5(2x-5)=3(2x-11)
11) 0.5x+3=1.2x+5.8

Answer 1

Ahmad is 7 years older than Bala. Four years ago, Ahmad was twice as old as Bala. Find the sum of their ages in 7 years' time.

Answer 2

A father is three times as old as his son. In 13 years' time, the father will only be twice as old as his son. Find their present ages.
(Please show the solutions clearly)

Answer 3

If you are studying this topic, surely you can't be having problems with every one of them.
Can you tell us where you are having problems ?

I will do the 1st of the age problems:

present time:
Bala --- x
Ahmad -- x+7

Four years ago:
Bala --- x-4
Ahmad -- x+7 - 4 = x+3
At that time "Ahmad was twice as old as Bala"
---> x+3 = 2(x-4)
x+3 = 2x-8
-x = -11
x = 11

so right now, Bala is 11 and Ahmad is 18
in 7 yrs from now:
Bala will be 18 and Ahmad will be 25

Set up the second one in a similar way.