Question

A textbook store sold a combined total of 274 psychology and biology textbooks in a week. The number of psychology textbooks sold was 78 more than the number of biology textbooks sold. How many textbooks of each type were sold?

Answer 1

Answer:176 psychology textbooks and 98 Biology textbooks were sold.

Step-by-step explanation:

Let x represent the number of psychology textbooks that were sold.

Let y represent the number of biology textbooks that were sold.

textbook store sold a combined total of 274 psychology and biology textbooks in a week. This means that

x + y = 274 - - - - - - - - - - -1

The number of psychology textbooks sold was 78 more than the number of biology textbooks sold. This means that

x = y + 78

Substituting x = y + 78 into equation 1, it becomes

y + 78 + y = 274

2y = 274 - 78

2y = 196

y = 98

x = y + 78 = 98 + 78

x = 176

Answer 2

Answer:psychology books sold=173

Biology books sold=95

Step-by-step explanation:

Psychology textbooks sold=p

Biology textbooks sold=b

P+b=274

P-78=b

P+P-78=274

2P-78=274

2P=274+78

2P=352

P=352/2

P=173

Substance P=173 in P-78=b

173-78=b

95=b b=95