One reason would be if you did not know the answer so you could do
4-5=x
another reason would be if the problem gave you the answer but not one of the things to get the answer
4-x=-1
not sure if that is what you want but I hope this helped
Answer:
If you consume less energy you pay less with respect to the amount of energy you saved. If you saved 16% of total energy you should expect to lower your bill by 16%. Count how much is left -> 1900-1900*0.16=1596$
if we take 30 to be the 100%, what is 27 off of it in percentage?

Answer:
Step-by-step explanation:
1 table and 2 chairs (2-seat table)
1 table and 4 chairs (4-seat table)
120 people so we need 120 chairs
Some Possibilities :
120 /4 = 30
0( 2-seat table) and 30 (4- seat tables) because 0·2 + 30·4 = 0+120 = 120
2( 2-seat table) and 29 (4- seat tables) because 2·2 + 29·4 = 4+ 116= 120
4( 2-seat table) and 28 (4- seat tables) because 4·2 + 28·4 = 8+ 112= 120
...
120/2 = 60
60( 2-seat table) and 0 (4- seat tables) because 60·2 + 0·4 = 120 + 0 = 120
58( 2-seat table) and 1 (4- seat tables) because 58·2 + 1·4 = 116 + 4 = 120
56( 2-seat table) and 2 (4- seat tables) because 56·2 + 2·4 = 112 + 8 = 120
...