Kelly spent 45 dollars more on boots than she did on a pair of jeans she spent 79.50 how much did she spend on jeans

79.50 - 45 = 34.5

she spent $34.5 on jeans.

"45 dollars more": +45

Total spent: 79.50

x=jeans

x+(45+x)=79.50

2x+45=79.50

2x=79.50-45

2x=34.5

x=34.5/2

x=17.25

This means that the jeans were $17.25 a pair. 

Thus, $45+$17.25 = $62.25, so we can check:

$62.25+$17.25 = $79.50

Thus the jeans were $17.25.