A textbook store sold a combined total of 323 math and psychology textbooks in a week. The number of psychology textbooks sold was 65 less than the number of math textbooks sold. How many textbooks of each type were sold?

Respuesta :

Answer:

There were 194 math textbooks and 129 Psychology textbooks sold

Step-by-step explanation:

Lets write some equations where M=math books and P= psych books:

1) M+P=323

2) P=M-65

1) Substitute M-65 as P in the first equation:

M+M-65=323

2) Combine alike terms:

2M-65=323

3) Add 65 to both sides:

2M=388

4) Divide both sides by 2:

M=194

5) Now, substitute 194 as M in the second equation:

P=194-65

6) Subtract:

P=129