Answer:
12.60
Step-by-step explanation:
Start off by the total which is 18. To find the percentage off you will have to make the 30% into a decimal, so simply move it two spaces to the left. Now you have .30. Multiply the decimal, .30, and the full amount, 18. Your equation now should be (.30)*(18). Your answer will be 5.40. 5.40 is what is off of the shirt from the original price, so subtract 5.40 from 18. Your equation now is (18-5.40) which is 12.60.
10 x 25 = 250, well 20 x 25 is just double that, its 10 doubled x 25 so he probably just added it up. repeated addition really helps with times tables.
