Thank you and can you help me with 36=1+7a

36 = 1 + 7a ( shift 1 over and you get - 1)
36 - 1 = 7a
35 = 7a ( shift 7 over and you get 35 divided by 7 )
5 = a

Idu

Whenever you move a number across the equal sign, the sign changes too.

For example

2 = 1 + a
Shift 1 over across, you get:
2 - 1 = a
1 = a
To double check,
2 = 1 + a
Since a is 1
2 = 1 + 1
2 = 2
So "a" must be 1

Another example:
5 = a - 7
Shift ( - 7 ) across, you get 5 + 7 = a
12 = a
To double check,
5 = a - 7
Since a is 12,
5 = 12 - 7
5 = 5
So "a" must be 12.

For division and multiplication, when you shift across the equal sign, the sign changes too

Example

5a = 10
Shift 5 over, you get
a = 10 ÷ 5
a = 2
To double check,
5a = 10
Since "a" is 2,
5 x 2 = 10
10 = 10

Another example:

2a = 10
Shift 2 over,
a = 10 ÷ 2
a = 5
To double check,
2a = 10
Since "a" is 5,
2 x 5 = 10
10 = 10