Because 2r+5=7, the minus 6 and 7 which gives you 1 then minus 4 and 1 witch is 3 then you do 10r-3 and it will get you to 2r+5=7 again. I hope this helped!
Make 4 7/8 into an improper fraction, that would be 39/8. So now you have to multiply 15/1 times 39/8 which would be 585/8 now you have to simplify that, which turns into 73
