the second question

If the power consumption during peak hours is x kWh, the power consumption during low hours is (136-x) kWh.

Judging from the meaning of the question.

0.55x=0.30( 136-x)

Solve it yourself

Third question

(47-x)÷(20-x)=4

Multiply the left and right sides by (20-x) and you get

47 times =80 times

solve

x= 1 1

Test: bringing x =11,20-x≠0.

Then the solution of the original fractional equation is x= 1 1.

The fourth question

5x + 14=7X -4

Move items, get

5x-7x=-4- 14

Merge similar projects to obtain

-2x=- 18

solve

x=9