Hi Ponie
Simplify both sides of the equation
3-x/5-4-x/2=1
3+ -1/5 x+ -4+ -1/2 x =1
Combine like terms
(-1/5 x + -1/2 x)+(3+-4)=1
-7/10 x +-1=1
-7/10 x -1=1
Add 1 to both sides
-7/10 x-1+1=1+1
-7/10 x=2
Multiply both sides by 10/-7
(10/-7)*(-7/10 x )= (10/-7)*2
x= -20/7
I hope that's help and I am sorry for the late answer !