First you multiply 4 by 5 and wind up with 20 Then you multiply four by 7÷9. That gets you 28÷9 You take out all the nines you can from 28, three in this case. That gets you 27÷9 + 1÷9 Your total thing is 20+27÷9+1÷9 That equals 20+3+1÷9 That equals 23 and 1÷9