On each of 7 Mondays, it rained 1.5 centimeters. On each of 9 Tuesdays it rained 2.5 centimeters. How many more centimeters did it rain on Tuesdays than Mondays?
Mondays: 7 * 1.5 = 
<gadget id="calculator">7*1.5</gadget>
<output>10.5</output>
10.5.
Tuesdays: 9 * 2.5 = 
<gadget id="calculator">9*2.5</gadget>
<output>22.5</output>
22.5
22.5 - 10.5 = 
<gadget id="calculator">22.5-10.5</gadget>
<output>12</output>
12 cm.
It rained 12 centimeters more on Tuesdays than on Mondays.

<result>12</result>