Question

b – 7 = 21

How do I work this out?

Answer 1

add 7 to both sides so b=28

Answer 2

b+7= 7
21 +7 = 28
Taht right?

Answer 3

no

Answer 4

b - 7 = 21

say that equation out loud : the number b minus seven is equal to twenty one
what can b be?
Can you think of a number such that if you subtract seven from it, you get 21?
In other words, if you add 7 to 21 , you get such a number. that number is 28. you can verify it.
twenty eight minus 7 is twenty one. therefore b is 28