Question

Every boy and girl _____ (was/were) ready. ​

Answer 1

Answer :-

Every boy and girl was ready.

Explanation :-

According to the rule of Subject Verb Agreement -

★ 'Everyone', 'every' , 'someone' , 'no one', 'nobody' , 'everybody' and 'each' take a singular verb.

Lets fill the blanks with both options, 

1. Every boy and girl was ready.

2. Every boy and girl were ready.

★ Remember the basic rule : 

Singular Subject → Plural noun.

Plural Subject → Singular noun. 

Example : 

1. She likes to eat.

2. They like to eat.

So, the sentences Given in the question , only one of them have the subject and Verb agreed. 

1. Every boy and girl was ready.

2. Every boy and girl were ready.

In Sentence 1. Subject 'Every girl and boy ' is Singular which agrees with verb 'was' (according to the basic rule) 

Therefore sentence 2. is wrong. 

'were ' is not the answer.

Therefore the answer is - 

Every boy and girl was ready

Answer 2

Every boy and girl was ready.

Hope it helps you.......