A textbook store sold a combined total of 426 math and sociology textbooks in a week. The number of math textbooks sold was 88 more than the number of sociology textbooks sold. How many textbooks of each type were sold?

Let m and s be the number of math and sociology books sold respectively.

m=s+88 we are also told that:

m+s=426, using m found above in this equation gives you:

s+88+s=426 combine like terms on left side

2s+88=426 subtract 88 from both sides

2s=338 divide both sides by 2

s=169, since m=s+88

m=169+88=257

So 257 math and 169 sociology textbooks were sold.