Question

A textbook store sold a combined total of 229 physics and math textbooks in a week. The number of math textbooks sold was 63 less than the number of physics textbooks sold. How many textbooks of each type were sold?

Answer 1

p+m = 229
m = p-63
now solve as usual

Answer 2

m = math textbooks

p = physics textbooks

A textbook store sold a combined total of 229 physics and math textbooks in a week means:

m + p = 229

The number of math textbooks sold was 63 less than the number of physics textbooks sold means:

m = p - 63

Replace m with p - 63 in equation

m + p = 229

p - 63 + p = 229

2 p - 63 = 229

Add 63 to both sides

2 p = 292

p = 292 / 2 = 146

m = p - 63 = 146 - 63 = 83

83 math textbooks

146 physics textbooks