Looks like distributive property 5 times 5 is 25, 5 times a -5i is -25i , 5i times 5 is positive 25i , 5i times 5i gives you , 25 i squared , so now you combine like terms , you have 25 -25i + 25i - 25i squared , cross out -25i and the positive 25i anf your left with 25-25 squared .
So if he already biked 25 miles we can subtract 80 and 25 which will get a total of 55. if we divided 55 miles to the rest of the 5 days he will have to bike 11 miles each day
