0.4x - 0.1y = 2
0.2x + 0.5y = 1
Solve the system

Explanation:
The starting system is:
{
0.4
x
−
0.1
y
=
2
0.2
x
+
0.5
y
=
1

If we multiply the second equation by
−
2
the coefficients of
x
will be opposite numbers:
{
0.4
x
−
0.1
y
=
2
−
0.4
x
−
y
=
−
2

Now we can add both sides of the equations to get an euation of 1 variable:
−
1.1
y
=
0

y
=
0

Now we have to substitute the calculated value of
y
to calculate
x
:
0.4
x
=
2

x
=
2
0.4
=
20
4
=
5

The solution of this systemm is:
{
x= 5
Y=0

I hope that helps let me know if you have questions.

Cancelling equ
Step 1
Make y same by multiplying 2 with ( 0.4x - 0.1y = 2 )

New equ is 2x - 0.5y =10

Step 2 cancelling y ( why? :- they are both same number and opposite sign and the main rules to cancel)

And ur left with
2x = 10 -> equ 1
0.2x = 1 -> equ 2

Step 3 Subtract equ 2 with equ 1
(0.2x - 2x = 1.8x)
(10 - 1 = 9 )

Ur left with this
1.8x = 9

Step 4 solve
x = 9/1.8
x = 5

Step 4 substitute x in the equ that was given to u from the start
Make y subject And solve

Y=0

The answer is 25uthere is no v in the question